ubuntu-cve-2021-47996
Vulnerability from osv_ubuntu
Published
2026-08-25 16:16
Modified
2026-09-02 15:41
Summary
Details
Nokogiri before 1.11.4 (CRuby implementation only, when the packaged/vendored libxml2 is used) bundles libxml2 2.9.10, which is affected by multiple vulnerabilities addressed in libxml2 2.9.12, including a memory leak in xmlSchemaValidateStream (CVE-2019-20388), a global buffer over-read in xmlEncodeEntitiesInternal (CVE-2020-24977), a heap-based buffer overflow (CVE-2021-3517), and an out-of-bounds read (CVE-2021-3518). Processing crafted XML documents may lead to denial of service, information disclosure, or memory corruption.
Severity
7.5 (High)
N/A (UNKNOWN)
References
{
"affected": [
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-nokogiri",
"binary_version": "1.6.1+ds-1ubuntu0.1~esm1"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:14.04:LTS",
"name": "ruby-nokogiri",
"purl": "pkg:deb/ubuntu/ruby-nokogiri@1.6.1+ds-1ubuntu0.1~esm1?arch=source\u0026distro=esm-infra-legacy/trusty"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.5.9-2",
"1.5.9-3",
"1.6.0-1",
"1.6.1+ds-1",
"1.6.1+ds-1ubuntu0.1~esm1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-nokogiri",
"binary_version": "1.6.7.2-3ubuntu0.1"
}
]
},
"package": {
"ecosystem": "Ubuntu:16.04:LTS",
"name": "ruby-nokogiri",
"purl": "pkg:deb/ubuntu/ruby-nokogiri@1.6.7.2-3ubuntu0.1?arch=source\u0026distro=xenial"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.6.6.2+ds-2build2",
"1.6.6.3-1",
"1.6.7-1",
"1.6.7.1-1",
"1.6.7.2-3",
"1.6.7.2-3build1",
"1.6.7.2-3ubuntu0.1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-nokogiri",
"binary_version": "1.8.2-1ubuntu0.1"
}
]
},
"package": {
"ecosystem": "Ubuntu:18.04:LTS",
"name": "ruby-nokogiri",
"purl": "pkg:deb/ubuntu/ruby-nokogiri@1.8.2-1ubuntu0.1?arch=source\u0026distro=bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.8.0-1",
"1.8.1-1",
"1.8.1-1build1",
"1.8.2-1build1",
"1.8.2-1ubuntu0.1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-nokogiri",
"binary_version": "1.10.7+dfsg1-2ubuntu0.1~esm2"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:20.04:LTS",
"name": "ruby-nokogiri",
"purl": "pkg:deb/ubuntu/ruby-nokogiri@1.10.7+dfsg1-2ubuntu0.1~esm2?arch=source\u0026distro=esm-apps/focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.10.3+dfsg1-2",
"1.10.4+dfsg1-1",
"1.10.7+dfsg1-1",
"1.10.7+dfsg1-2",
"1.10.7+dfsg1-2build1",
"1.10.7+dfsg1-2ubuntu0.1~esm2"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-nokogiri",
"binary_version": "1.13.1+dfsg-2ubuntu0.1~esm1"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:22.04:LTS",
"name": "ruby-nokogiri",
"purl": "pkg:deb/ubuntu/ruby-nokogiri@1.13.1+dfsg-2ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.11.1+dfsg-2ubuntu1",
"1.11.7+dfsg-3",
"1.11.7+dfsg-3build1",
"1.13.1+dfsg-2",
"1.13.1+dfsg-2ubuntu0.1~esm1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-nokogiri",
"binary_version": "1.16.2+dfsg-1build1"
}
]
},
"package": {
"ecosystem": "Ubuntu:24.04:LTS",
"name": "ruby-nokogiri",
"purl": "pkg:deb/ubuntu/ruby-nokogiri@1.16.2+dfsg-1build1?arch=source\u0026distro=noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.14.3+dfsg-2",
"1.16.2+dfsg-1",
"1.16.2+dfsg-1build1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "ruby-nokogiri",
"binary_version": "1.18.10+dfsg-3"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "ruby-nokogiri",
"purl": "pkg:deb/ubuntu/ruby-nokogiri@1.18.10+dfsg-3?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.18.2+dfsg-1build1",
"1.18.10+dfsg-2",
"1.18.10+dfsg-3"
]
}
],
"aliases": [],
"details": "Nokogiri before 1.11.4 (CRuby implementation only, when the packaged/vendored libxml2 is used) bundles libxml2 2.9.10, which is affected by multiple vulnerabilities addressed in libxml2 2.9.12, including a memory leak in xmlSchemaValidateStream (CVE-2019-20388), a global buffer over-read in xmlEncodeEntitiesInternal (CVE-2020-24977), a heap-based buffer overflow (CVE-2021-3517), and an out-of-bounds read (CVE-2021-3518). Processing crafted XML documents may lead to denial of service, information disclosure, or memory corruption.",
"id": "UBUNTU-CVE-2021-47996",
"modified": "2026-09-02T15:41:52Z",
"published": "2026-08-25T16:16:00Z",
"references": [
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2021-47996"
},
{
"type": "REPORT",
"url": "https://www.cve.org/CVERecord?id=CVE-2021-47996"
},
{
"type": "REPORT",
"url": "https://github.com/GNOME/libxml2/commit/0e1a49c8907645d2e155f0d89d4d9895ac5112b5"
},
{
"type": "REPORT",
"url": "https://github.com/GNOME/libxml2/commit/1098c30a040e72a4654968547f415be4e4c40fe7"
},
{
"type": "REPORT",
"url": "https://github.com/GNOME/libxml2/commit/1358d157d0bd83be1dfe356a69213df9fac0b539"
},
{
"type": "REPORT",
"url": "https://github.com/GNOME/libxml2/commit/50f06b3efb638efb0abd95dc62dca05ae67882c2"
},
{
"type": "REPORT",
"url": "https://github.com/GNOME/libxml2/commit/7ffcd44d7e6c46704f8af0321d9314cd26e0e18a"
},
{
"type": "REPORT",
"url": "https://github.com/GNOME/libxml2/commit/8598060bacada41a0eb09d95c97744ff4e428f8e"
},
{
"type": "REPORT",
"url": "https://github.com/GNOME/libxml2/commit/babe75030c7f64a37826bb3342317134568bef61"
},
{
"type": "REPORT",
"url": "https://github.com/GNOME/libxml2/commit/bf22713507fe1fc3a2c4b525cf0a88c2dc87a3a2"
},
{
"type": "REPORT",
"url": "https://github.com/sparklemotion/nokogiri/security/advisories/GHSA-7rrm-v45f-jp64"
},
{
"type": "REPORT",
"url": "https://www.vulncheck.com/advisories/nokogiri-before-multiple-vulnerabilities-via-libxml2"
}
],
"related": [],
"schema_version": "1.7.0",
"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"
},
{
"score": "medium",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2021-47996"
]
}
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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.
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.
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