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PYSEC-2021-108
Vulnerability from pysec - Published: 2021-06-29 11:15 - Updated: 2021-07-02 18:56
VLAI
Details
An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component, the authority regular expression exhibits catastrophic backtracking, causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.
Impacted products
| Name | purl | urllib3 | pkg:pypi/urllib3 |
|---|
Aliases
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "urllib3",
"purl": "pkg:pypi/urllib3"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2d4a3fee6de2fa45eb82169361918f759269b4ec"
}
],
"repo": "https://github.com/urllib3/urllib3",
"type": "GIT"
},
{
"events": [
{
"introduced": "1.25.4"
},
{
"fixed": "1.26.5"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.25.4",
"1.25.5",
"1.25.6",
"1.25.7",
"1.25.8",
"1.25.9",
"1.25.10",
"1.25.11",
"1.26.0",
"1.26.1",
"1.26.2",
"1.26.3",
"1.26.4"
]
}
],
"aliases": [
"CVE-2021-33503",
"GHSA-q2q7-5pp4-w6pg"
],
"details": "An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component, the authority regular expression exhibits catastrophic backtracking, causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.",
"id": "PYSEC-2021-108",
"modified": "2021-07-02T18:56:20.858344Z",
"published": "2021-06-29T11:15:00Z",
"references": [
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "FIX",
"url": "https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec"
}
]
}
BREW-ABI3AUDIT-CVE-2021-33503 (GHSA-Q2Q7-5PP4-W6PG)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:34 – Updated: 2026-09-10 18:49 – Source website
VLAI
Summary
Catastrophic backtracking in URL authority parser when passed URL containing many @ characters
Details
Impact
When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.
Patches
The issue has been fixed in urllib3 v1.26.5.
References
For more information
If you have any questions or comments about this advisory: * Ask in our community Discord * Email sethmichaellarson@gmail.com
Severity
References
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "urllib3",
"resource_purl": "pkg:pypi/urllib3@2.7.0",
"upstream_fixed_in": "1.26.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "abi3audit",
"purl": "pkg:brew/abi3audit"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.0.26_4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/urllib3@2.7.0",
"name": "urllib3",
"resource": "urllib3",
"strategy": "registry",
"subject_version": "2.7.0"
}
]
},
"details": "### Impact\n\nWhen provided with a URL containing many `@` characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.\n\n\n### Patches\n\nThe issue has been fixed in urllib3 v1.26.5.\n\n### References\n\n- [CVE-2021-33503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33503)\n- [JVNVU#92413403 (English)](https://jvn.jp/en/vu/JVNVU92413403/)\n- [JVNVU#92413403 (Japanese)](https://jvn.jp/vu/JVNVU92413403/)\n- [urllib3 v1.26.5](https://github.com/urllib3/urllib3/releases/tag/1.26.5)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Ask in our [community Discord](https://discord.gg/urllib3)\n* Email [sethmichaellarson@gmail.com](mailto:sethmichaellarson@gmail.com)",
"id": "BREW-abi3audit-CVE-2021-33503",
"modified": "2026-09-10T18:49:43Z",
"published": "2026-08-13T16:34:56Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33503"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/5b047b645f5f93900d5e2fc31230848c25eb1f5f#diff-52026d639119bf1e0364836b4e8a18bd9ed3c95c6ba39b26534a5057a65e35bbR65"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2021-108.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/urllib3/urllib3"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FMUGWEAUYGGHTPPXT6YBD53WYXQGVV73"
},
{
"type": "WEB",
"url": "https://security.gentoo.org/glsa/202107-36"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Catastrophic backtracking in URL authority parser when passed URL containing many @ characters",
"upstream": [
"GHSA-q2q7-5pp4-w6pg",
"CVE-2021-33503",
"PYSEC-2021-108"
]
}
BREW-AIDER-CVE-2021-33503 (GHSA-Q2Q7-5PP4-W6PG)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:35 – Updated: 2026-09-09 23:40 – Source website
VLAI
Summary
Catastrophic backtracking in URL authority parser when passed URL containing many @ characters
Details
Impact
When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.
Patches
The issue has been fixed in urllib3 v1.26.5.
References
For more information
If you have any questions or comments about this advisory: * Ask in our community Discord * Email sethmichaellarson@gmail.com
Severity
References
| URL | Type | ||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "urllib3",
"resource_purl": "pkg:pypi/urllib3@2.6.3",
"upstream_fixed_in": "1.26.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "aider",
"purl": "pkg:brew/aider"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.86.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/urllib3@2.6.3",
"name": "urllib3",
"resource": "urllib3",
"strategy": "registry",
"subject_version": "2.6.3"
}
]
},
"details": "### Impact\n\nWhen provided with a URL containing many `@` characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.\n\n\n### Patches\n\nThe issue has been fixed in urllib3 v1.26.5.\n\n### References\n\n- [CVE-2021-33503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33503)\n- [JVNVU#92413403 (English)](https://jvn.jp/en/vu/JVNVU92413403/)\n- [JVNVU#92413403 (Japanese)](https://jvn.jp/vu/JVNVU92413403/)\n- [urllib3 v1.26.5](https://github.com/urllib3/urllib3/releases/tag/1.26.5)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Ask in our [community Discord](https://discord.gg/urllib3)\n* Email [sethmichaellarson@gmail.com](mailto:sethmichaellarson@gmail.com)",
"id": "BREW-aider-CVE-2021-33503",
"modified": "2026-09-09T23:40:56Z",
"published": "2026-08-13T16:35:12Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33503"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/5b047b645f5f93900d5e2fc31230848c25eb1f5f#diff-52026d639119bf1e0364836b4e8a18bd9ed3c95c6ba39b26534a5057a65e35bbR65"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2021-108.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/urllib3/urllib3"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FMUGWEAUYGGHTPPXT6YBD53WYXQGVV73"
},
{
"type": "WEB",
"url": "https://security.gentoo.org/glsa/202107-36"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Catastrophic backtracking in URL authority parser when passed URL containing many @ characters",
"upstream": [
"GHSA-q2q7-5pp4-w6pg",
"CVE-2021-33503",
"PYSEC-2021-108"
]
}
BREW-AIRSHARE-CVE-2021-33503 (GHSA-Q2Q7-5PP4-W6PG)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:35 – Updated: 2026-09-17 19:58 – Source website
VLAI
Summary
Catastrophic backtracking in URL authority parser when passed URL containing many @ characters
Details
Impact
When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.
Patches
The issue has been fixed in urllib3 v1.26.5.
References
For more information
If you have any questions or comments about this advisory: * Ask in our community Discord * Email sethmichaellarson@gmail.com
Severity
References
| URL | Type | ||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "urllib3",
"resource_purl": "pkg:pypi/urllib3@2.7.0",
"upstream_fixed_in": "1.26.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "airshare",
"purl": "pkg:brew/airshare"
},
"ranges": [
{
"events": [
{
"introduced": "0.1.5"
},
{
"fixed": "0.1.6_3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/urllib3@2.7.0",
"name": "urllib3",
"resource": "urllib3",
"strategy": "registry",
"subject_version": "2.7.0"
}
]
},
"details": "### Impact\n\nWhen provided with a URL containing many `@` characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.\n\n\n### Patches\n\nThe issue has been fixed in urllib3 v1.26.5.\n\n### References\n\n- [CVE-2021-33503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33503)\n- [JVNVU#92413403 (English)](https://jvn.jp/en/vu/JVNVU92413403/)\n- [JVNVU#92413403 (Japanese)](https://jvn.jp/vu/JVNVU92413403/)\n- [urllib3 v1.26.5](https://github.com/urllib3/urllib3/releases/tag/1.26.5)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Ask in our [community Discord](https://discord.gg/urllib3)\n* Email [sethmichaellarson@gmail.com](mailto:sethmichaellarson@gmail.com)",
"id": "BREW-airshare-CVE-2021-33503",
"modified": "2026-09-17T19:58:50Z",
"published": "2026-08-13T16:35:13Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33503"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/5b047b645f5f93900d5e2fc31230848c25eb1f5f#diff-52026d639119bf1e0364836b4e8a18bd9ed3c95c6ba39b26534a5057a65e35bbR65"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2021-108.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/urllib3/urllib3"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FMUGWEAUYGGHTPPXT6YBD53WYXQGVV73"
},
{
"type": "WEB",
"url": "https://security.gentoo.org/glsa/202107-36"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Catastrophic backtracking in URL authority parser when passed URL containing many @ characters",
"upstream": [
"GHSA-q2q7-5pp4-w6pg",
"CVE-2021-33503",
"PYSEC-2021-108"
]
}
BREW-AIVEN-CLIENT-CVE-20… (GHSA-Q2Q7-5PP4-W6PG)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:35 – Updated: 2026-09-09 23:40 – Source website
VLAI
Summary
Catastrophic backtracking in URL authority parser when passed URL containing many @ characters
Details
Impact
When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.
Patches
The issue has been fixed in urllib3 v1.26.5.
References
For more information
If you have any questions or comments about this advisory: * Ask in our community Discord * Email sethmichaellarson@gmail.com
Severity
References
| URL | Type | ||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "urllib3",
"resource_purl": "pkg:pypi/urllib3@2.7.0",
"upstream_fixed_in": "1.26.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "aiven-client",
"purl": "pkg:brew/aiven-client"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.16.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/urllib3@2.7.0",
"name": "urllib3",
"resource": "urllib3",
"strategy": "registry",
"subject_version": "2.7.0"
}
]
},
"details": "### Impact\n\nWhen provided with a URL containing many `@` characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.\n\n\n### Patches\n\nThe issue has been fixed in urllib3 v1.26.5.\n\n### References\n\n- [CVE-2021-33503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33503)\n- [JVNVU#92413403 (English)](https://jvn.jp/en/vu/JVNVU92413403/)\n- [JVNVU#92413403 (Japanese)](https://jvn.jp/vu/JVNVU92413403/)\n- [urllib3 v1.26.5](https://github.com/urllib3/urllib3/releases/tag/1.26.5)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Ask in our [community Discord](https://discord.gg/urllib3)\n* Email [sethmichaellarson@gmail.com](mailto:sethmichaellarson@gmail.com)",
"id": "BREW-aiven-client-CVE-2021-33503",
"modified": "2026-09-09T23:40:58Z",
"published": "2026-08-13T16:35:13Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33503"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/5b047b645f5f93900d5e2fc31230848c25eb1f5f#diff-52026d639119bf1e0364836b4e8a18bd9ed3c95c6ba39b26534a5057a65e35bbR65"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2021-108.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/urllib3/urllib3"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FMUGWEAUYGGHTPPXT6YBD53WYXQGVV73"
},
{
"type": "WEB",
"url": "https://security.gentoo.org/glsa/202107-36"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Catastrophic backtracking in URL authority parser when passed URL containing many @ characters",
"upstream": [
"GHSA-q2q7-5pp4-w6pg",
"CVE-2021-33503",
"PYSEC-2021-108"
]
}
BREW-ANSIBLE-CVE-2021-33503 (GHSA-Q2Q7-5PP4-W6PG)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:35 – Updated: 2026-09-09 23:41 – Source website
VLAI
Summary
Catastrophic backtracking in URL authority parser when passed URL containing many @ characters
Details
Impact
When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.
Patches
The issue has been fixed in urllib3 v1.26.5.
References
For more information
If you have any questions or comments about this advisory: * Ask in our community Discord * Email sethmichaellarson@gmail.com
Severity
References
| URL | Type | ||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "urllib3",
"resource_purl": "pkg:pypi/urllib3@2.7.0",
"upstream_fixed_in": "1.26.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "ansible",
"purl": "pkg:brew/ansible"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "14.3.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/urllib3@2.7.0",
"name": "urllib3",
"resource": "urllib3",
"strategy": "registry",
"subject_version": "2.7.0"
}
]
},
"details": "### Impact\n\nWhen provided with a URL containing many `@` characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.\n\n\n### Patches\n\nThe issue has been fixed in urllib3 v1.26.5.\n\n### References\n\n- [CVE-2021-33503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33503)\n- [JVNVU#92413403 (English)](https://jvn.jp/en/vu/JVNVU92413403/)\n- [JVNVU#92413403 (Japanese)](https://jvn.jp/vu/JVNVU92413403/)\n- [urllib3 v1.26.5](https://github.com/urllib3/urllib3/releases/tag/1.26.5)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Ask in our [community Discord](https://discord.gg/urllib3)\n* Email [sethmichaellarson@gmail.com](mailto:sethmichaellarson@gmail.com)",
"id": "BREW-ansible-CVE-2021-33503",
"modified": "2026-09-09T23:41:05Z",
"published": "2026-08-13T16:35:22Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33503"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/5b047b645f5f93900d5e2fc31230848c25eb1f5f#diff-52026d639119bf1e0364836b4e8a18bd9ed3c95c6ba39b26534a5057a65e35bbR65"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2021-108.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/urllib3/urllib3"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FMUGWEAUYGGHTPPXT6YBD53WYXQGVV73"
},
{
"type": "WEB",
"url": "https://security.gentoo.org/glsa/202107-36"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Catastrophic backtracking in URL authority parser when passed URL containing many @ characters",
"upstream": [
"GHSA-q2q7-5pp4-w6pg",
"CVE-2021-33503",
"PYSEC-2021-108"
]
}
BREW-ANSIBLE@10-CVE-2021-33503 (GHSA-Q2Q7-5PP4-W6PG)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:35 – Updated: 2026-09-09 23:41 – Source website
VLAI
Summary
Catastrophic backtracking in URL authority parser when passed URL containing many @ characters
Details
Impact
When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.
Patches
The issue has been fixed in urllib3 v1.26.5.
References
For more information
If you have any questions or comments about this advisory: * Ask in our community Discord * Email sethmichaellarson@gmail.com
Severity
References
| URL | Type | ||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "urllib3",
"resource_purl": "pkg:pypi/urllib3@2.3.0",
"upstream_fixed_in": "1.26.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "ansible@10",
"purl": "pkg:brew/ansible%4010"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "10.7.0_6"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/urllib3@2.3.0",
"name": "urllib3",
"resource": "urllib3",
"strategy": "registry",
"subject_version": "2.3.0"
}
]
},
"details": "### Impact\n\nWhen provided with a URL containing many `@` characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.\n\n\n### Patches\n\nThe issue has been fixed in urllib3 v1.26.5.\n\n### References\n\n- [CVE-2021-33503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33503)\n- [JVNVU#92413403 (English)](https://jvn.jp/en/vu/JVNVU92413403/)\n- [JVNVU#92413403 (Japanese)](https://jvn.jp/vu/JVNVU92413403/)\n- [urllib3 v1.26.5](https://github.com/urllib3/urllib3/releases/tag/1.26.5)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Ask in our [community Discord](https://discord.gg/urllib3)\n* Email [sethmichaellarson@gmail.com](mailto:sethmichaellarson@gmail.com)",
"id": "BREW-ansible@10-CVE-2021-33503",
"modified": "2026-09-09T23:41:06Z",
"published": "2026-08-13T16:35:22Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33503"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/5b047b645f5f93900d5e2fc31230848c25eb1f5f#diff-52026d639119bf1e0364836b4e8a18bd9ed3c95c6ba39b26534a5057a65e35bbR65"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2021-108.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/urllib3/urllib3"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FMUGWEAUYGGHTPPXT6YBD53WYXQGVV73"
},
{
"type": "WEB",
"url": "https://security.gentoo.org/glsa/202107-36"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Catastrophic backtracking in URL authority parser when passed URL containing many @ characters",
"upstream": [
"GHSA-q2q7-5pp4-w6pg",
"CVE-2021-33503",
"PYSEC-2021-108"
]
}
BREW-ANSIBLE@12-CVE-2021-33503 (GHSA-Q2Q7-5PP4-W6PG)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:35 – Updated: 2026-09-09 23:41 – Source website
VLAI
Summary
Catastrophic backtracking in URL authority parser when passed URL containing many @ characters
Details
Impact
When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.
Patches
The issue has been fixed in urllib3 v1.26.5.
References
For more information
If you have any questions or comments about this advisory: * Ask in our community Discord * Email sethmichaellarson@gmail.com
Severity
References
| URL | Type | ||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "urllib3",
"resource_purl": "pkg:pypi/urllib3@2.3.0",
"upstream_fixed_in": "1.26.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "ansible@12",
"purl": "pkg:brew/ansible%4012"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "12.3.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/urllib3@2.3.0",
"name": "urllib3",
"resource": "urllib3",
"strategy": "registry",
"subject_version": "2.3.0"
}
]
},
"details": "### Impact\n\nWhen provided with a URL containing many `@` characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.\n\n\n### Patches\n\nThe issue has been fixed in urllib3 v1.26.5.\n\n### References\n\n- [CVE-2021-33503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33503)\n- [JVNVU#92413403 (English)](https://jvn.jp/en/vu/JVNVU92413403/)\n- [JVNVU#92413403 (Japanese)](https://jvn.jp/vu/JVNVU92413403/)\n- [urllib3 v1.26.5](https://github.com/urllib3/urllib3/releases/tag/1.26.5)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Ask in our [community Discord](https://discord.gg/urllib3)\n* Email [sethmichaellarson@gmail.com](mailto:sethmichaellarson@gmail.com)",
"id": "BREW-ansible@12-CVE-2021-33503",
"modified": "2026-09-09T23:41:06Z",
"published": "2026-08-13T16:35:22Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33503"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/5b047b645f5f93900d5e2fc31230848c25eb1f5f#diff-52026d639119bf1e0364836b4e8a18bd9ed3c95c6ba39b26534a5057a65e35bbR65"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2021-108.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/urllib3/urllib3"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FMUGWEAUYGGHTPPXT6YBD53WYXQGVV73"
},
{
"type": "WEB",
"url": "https://security.gentoo.org/glsa/202107-36"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Catastrophic backtracking in URL authority parser when passed URL containing many @ characters",
"upstream": [
"GHSA-q2q7-5pp4-w6pg",
"CVE-2021-33503",
"PYSEC-2021-108"
]
}
BREW-ANSIBLE@13-CVE-2021-33503 (GHSA-Q2Q7-5PP4-W6PG)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:35 – Updated: 2026-09-10 18:51 – Source website
VLAI
Summary
Catastrophic backtracking in URL authority parser when passed URL containing many @ characters
Details
Impact
When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.
Patches
The issue has been fixed in urllib3 v1.26.5.
References
For more information
If you have any questions or comments about this advisory: * Ask in our community Discord * Email sethmichaellarson@gmail.com
Severity
References
| URL | Type | ||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "urllib3",
"resource_purl": "pkg:pypi/urllib3@2.7.0",
"upstream_fixed_in": "1.26.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "ansible@13",
"purl": "pkg:brew/ansible%4013"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "13.8.0_2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/urllib3@2.7.0",
"name": "urllib3",
"resource": "urllib3",
"strategy": "registry",
"subject_version": "2.7.0"
}
]
},
"details": "### Impact\n\nWhen provided with a URL containing many `@` characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.\n\n\n### Patches\n\nThe issue has been fixed in urllib3 v1.26.5.\n\n### References\n\n- [CVE-2021-33503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33503)\n- [JVNVU#92413403 (English)](https://jvn.jp/en/vu/JVNVU92413403/)\n- [JVNVU#92413403 (Japanese)](https://jvn.jp/vu/JVNVU92413403/)\n- [urllib3 v1.26.5](https://github.com/urllib3/urllib3/releases/tag/1.26.5)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Ask in our [community Discord](https://discord.gg/urllib3)\n* Email [sethmichaellarson@gmail.com](mailto:sethmichaellarson@gmail.com)",
"id": "BREW-ansible@13-CVE-2021-33503",
"modified": "2026-09-10T18:51:29Z",
"published": "2026-08-13T16:35:22Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33503"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/5b047b645f5f93900d5e2fc31230848c25eb1f5f#diff-52026d639119bf1e0364836b4e8a18bd9ed3c95c6ba39b26534a5057a65e35bbR65"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2021-108.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/urllib3/urllib3"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FMUGWEAUYGGHTPPXT6YBD53WYXQGVV73"
},
{
"type": "WEB",
"url": "https://security.gentoo.org/glsa/202107-36"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Catastrophic backtracking in URL authority parser when passed URL containing many @ characters",
"upstream": [
"GHSA-q2q7-5pp4-w6pg",
"CVE-2021-33503",
"PYSEC-2021-108"
]
}
BREW-ANSIBLE@9-CVE-2021-33503 (GHSA-Q2Q7-5PP4-W6PG)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:35 – Updated: 2026-09-09 23:41 – Source website
VLAI
Summary
Catastrophic backtracking in URL authority parser when passed URL containing many @ characters
Details
Impact
When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.
Patches
The issue has been fixed in urllib3 v1.26.5.
References
For more information
If you have any questions or comments about this advisory: * Ask in our community Discord * Email sethmichaellarson@gmail.com
Severity
References
| URL | Type | ||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "urllib3",
"resource_purl": "pkg:pypi/urllib3@2.3.0",
"upstream_fixed_in": "1.26.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "ansible@9",
"purl": "pkg:brew/ansible%409"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "9.13.0_4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/urllib3@2.3.0",
"name": "urllib3",
"resource": "urllib3",
"strategy": "registry",
"subject_version": "2.3.0"
}
]
},
"details": "### Impact\n\nWhen provided with a URL containing many `@` characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.\n\n\n### Patches\n\nThe issue has been fixed in urllib3 v1.26.5.\n\n### References\n\n- [CVE-2021-33503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33503)\n- [JVNVU#92413403 (English)](https://jvn.jp/en/vu/JVNVU92413403/)\n- [JVNVU#92413403 (Japanese)](https://jvn.jp/vu/JVNVU92413403/)\n- [urllib3 v1.26.5](https://github.com/urllib3/urllib3/releases/tag/1.26.5)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Ask in our [community Discord](https://discord.gg/urllib3)\n* Email [sethmichaellarson@gmail.com](mailto:sethmichaellarson@gmail.com)",
"id": "BREW-ansible@9-CVE-2021-33503",
"modified": "2026-09-09T23:41:06Z",
"published": "2026-08-13T16:35:23Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33503"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/5b047b645f5f93900d5e2fc31230848c25eb1f5f#diff-52026d639119bf1e0364836b4e8a18bd9ed3c95c6ba39b26534a5057a65e35bbR65"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2021-108.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/urllib3/urllib3"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FMUGWEAUYGGHTPPXT6YBD53WYXQGVV73"
},
{
"type": "WEB",
"url": "https://security.gentoo.org/glsa/202107-36"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Catastrophic backtracking in URL authority parser when passed URL containing many @ characters",
"upstream": [
"GHSA-q2q7-5pp4-w6pg",
"CVE-2021-33503",
"PYSEC-2021-108"
]
}
BREW-APM-CVE-2021-33503 (GHSA-Q2Q7-5PP4-W6PG)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:35 – Updated: 2026-09-10 18:52 – Source website
VLAI
Summary
Catastrophic backtracking in URL authority parser when passed URL containing many @ characters
Details
Impact
When provided with a URL containing many @ characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.
Patches
The issue has been fixed in urllib3 v1.26.5.
References
For more information
If you have any questions or comments about this advisory: * Ask in our community Discord * Email sethmichaellarson@gmail.com
Severity
References
| URL | Type | ||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "urllib3",
"resource_purl": "pkg:pypi/urllib3@2.7.0",
"upstream_fixed_in": "1.26.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "apm",
"purl": "pkg:brew/apm"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.28.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/urllib3@2.7.0",
"name": "urllib3",
"resource": "urllib3",
"strategy": "registry",
"subject_version": "2.7.0"
}
]
},
"details": "### Impact\n\nWhen provided with a URL containing many `@` characters in the authority component the authority regular expression exhibits catastrophic backtracking causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.\n\n\n### Patches\n\nThe issue has been fixed in urllib3 v1.26.5.\n\n### References\n\n- [CVE-2021-33503](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33503)\n- [JVNVU#92413403 (English)](https://jvn.jp/en/vu/JVNVU92413403/)\n- [JVNVU#92413403 (Japanese)](https://jvn.jp/vu/JVNVU92413403/)\n- [urllib3 v1.26.5](https://github.com/urllib3/urllib3/releases/tag/1.26.5)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Ask in our [community Discord](https://discord.gg/urllib3)\n* Email [sethmichaellarson@gmail.com](mailto:sethmichaellarson@gmail.com)",
"id": "BREW-apm-CVE-2021-33503",
"modified": "2026-09-10T18:52:52Z",
"published": "2026-08-13T16:35:55Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33503"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec"
},
{
"type": "WEB",
"url": "https://github.com/urllib3/urllib3/commit/5b047b645f5f93900d5e2fc31230848c25eb1f5f#diff-52026d639119bf1e0364836b4e8a18bd9ed3c95c6ba39b26534a5057a65e35bbR65"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-q2q7-5pp4-w6pg"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2021-108.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/urllib3/urllib3"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6SCV7ZNAHS3E6PBFLJGENCDRDRWRZZ6W"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FMUGWEAUYGGHTPPXT6YBD53WYXQGVV73"
},
{
"type": "WEB",
"url": "https://security.gentoo.org/glsa/202107-36"
},
{
"type": "WEB",
"url": "https://www.oracle.com/security-alerts/cpuoct2021.html"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Catastrophic backtracking in URL authority parser when passed URL containing many @ characters",
"upstream": [
"GHSA-q2q7-5pp4-w6pg",
"CVE-2021-33503",
"PYSEC-2021-108"
]
}
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Trend slope:
-
(linear fit over daily sighting counts)
Show additional events:
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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