usn-8077-1
Vulnerability from osv_ubuntu
Published
2026-03-05 16:04
Modified
2026-06-25 10:47
Summary
python-bleach vulnerabilities
Details
It was discovered that Bleach did not properly sanitize URI attributes containing character entities. An attacker could possibly use this issue to construct a URI with a disallowed scheme that would bypass sanitization, leading to cross-site scripting. This issue only affected Ubuntu 18.04 LTS. (CVE-2018-7753)
Yaniv Nizry discovered that Bleach was vulnerable to a mutation cross-site scripting issue when sanitizing HTML with the noscript tag and a raw tag in the allowed tags list. An attacker could possibly use this issue to inject malicious content, leading to cross-site scripting. This issue only affected Ubuntu 18.04 LTS. (CVE-2020-6802)
Yaniv Nizry discovered that Bleach was vulnerable to a mutation cross-site scripting issue when sanitizing HTML with RCDATA together with svg or math tags in the allowed tags list. An attacker could possibly use this issue to inject malicious content, leading to cross-site scripting. (CVE-2020-6816)
It was discovered that Bleach incorrectly handled parsing of style attributes when sanitizing HTML. An attacker could possibly use this issue to perform a regular expression denial of service, leading to excessive resource consumption. (CVE-2020-6817)
Yaniv Nizry and Michał Bentkowski discovered that Bleach was vulnerable to a mutation cross-site scripting issue when sanitizing HTML with certain combinations of allowed tags. An attacker could possibly use this issue to inject malicious content, leading to cross-site scripting. (CVE-2021-23980)
References
{
"affected": [
{
"database_specific": {
"cves_map": {
"cves": [
{
"id": "CVE-2020-6816",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
},
{
"id": "CVE-2020-6817",
"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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
},
{
"id": "CVE-2021-23980",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
}
],
"ecosystem": "Ubuntu:Pro:16.04:LTS"
}
},
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "python-bleach",
"binary_version": "1.4.2-1ubuntu0.1~esm1"
},
{
"binary_name": "python3-bleach",
"binary_version": "1.4.2-1ubuntu0.1~esm1"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:16.04:LTS",
"name": "python-bleach",
"purl": "pkg:deb/ubuntu/python-bleach@1.4.2-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/xenial"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.4.2-1ubuntu0.1~esm1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.4-1",
"1.4.2-1"
]
},
{
"database_specific": {
"cves_map": {
"cves": [
{
"id": "CVE-2018-7753",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
},
{
"id": "CVE-2020-6802",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
},
{
"id": "CVE-2020-6816",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
},
{
"id": "CVE-2020-6817",
"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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
},
{
"id": "CVE-2021-23980",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
}
],
"ecosystem": "Ubuntu:Pro:18.04:LTS"
}
},
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "python-bleach",
"binary_version": "2.1.2-1ubuntu0.1~esm1"
},
{
"binary_name": "python3-bleach",
"binary_version": "2.1.2-1ubuntu0.1~esm1"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:18.04:LTS",
"name": "python-bleach",
"purl": "pkg:deb/ubuntu/python-bleach@2.1.2-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.1.2-1ubuntu0.1~esm1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"2.0-1",
"2.1.2-1"
]
},
{
"database_specific": {
"cves_map": {
"cves": [
{
"id": "CVE-2020-6816",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
},
{
"id": "CVE-2020-6817",
"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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
},
{
"id": "CVE-2021-23980",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
]
}
],
"ecosystem": "Ubuntu:Pro:20.04:LTS"
}
},
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "python3-bleach",
"binary_version": "3.1.1-1ubuntu0.1~esm1"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:20.04:LTS",
"name": "python-bleach",
"purl": "pkg:deb/ubuntu/python-bleach@3.1.1-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.1.1-1ubuntu0.1~esm1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.1.0-1",
"3.1.0-2",
"3.1.1-1"
]
}
],
"aliases": [],
"details": "It was discovered that Bleach did not properly sanitize URI attributes\ncontaining character entities. An attacker could possibly use this issue\nto construct a URI with a disallowed scheme that would bypass\nsanitization, leading to cross-site scripting. This issue only affected\nUbuntu 18.04 LTS. (CVE-2018-7753)\n\nYaniv Nizry discovered that Bleach was vulnerable to a mutation\ncross-site scripting issue when sanitizing HTML with the noscript tag\nand a raw tag in the allowed tags list. An attacker could possibly\nuse this issue to inject malicious content, leading to cross-site\nscripting. This issue only affected Ubuntu 18.04 LTS. (CVE-2020-6802)\n\nYaniv Nizry discovered that Bleach was vulnerable to a mutation\ncross-site scripting issue when sanitizing HTML with RCDATA together\nwith svg or math tags in the allowed tags list. An attacker could\npossibly use this issue to inject malicious content, leading to\ncross-site scripting. (CVE-2020-6816)\n\nIt was discovered that Bleach incorrectly handled parsing of style\nattributes when sanitizing HTML. An attacker could possibly use this\nissue to perform a regular expression denial of service, leading to\nexcessive resource consumption. (CVE-2020-6817)\n\nYaniv Nizry and Micha\u0142 Bentkowski discovered that Bleach was vulnerable\nto a mutation cross-site scripting issue when sanitizing HTML with\ncertain combinations of allowed tags. An attacker could possibly use\nthis issue to inject malicious content, leading to cross-site scripting.\n(CVE-2021-23980)",
"id": "USN-8077-1",
"modified": "2026-06-25T10:47:32Z",
"published": "2026-03-05T16:04:13Z",
"references": [
{
"type": "ADVISORY",
"url": "https://ubuntu.com/security/notices/USN-8077-1"
},
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2018-7753"
},
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2020-6802"
},
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2020-6816"
},
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2020-6817"
},
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2021-23980"
}
],
"related": [],
"schema_version": "1.7.0",
"summary": "python-bleach vulnerabilities",
"upstream": [
"UBUNTU-CVE-2018-7753",
"UBUNTU-CVE-2020-6802",
"UBUNTU-CVE-2020-6816",
"UBUNTU-CVE-2020-6817",
"UBUNTU-CVE-2021-23980"
]
}
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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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