Summary
Nokogiri patches vendored libxml2 to resolve multiple CVEs
Nokogiri v1.18.9 patches the vendored libxml2 to address CVE-2025-6021, CVE-2025-6170, CVE-2025-49794, CVE-2025-49795, and CVE-2025-49796.
Impact and severity
CVE-2025-6021
A flaw was found in libxml2's xmlBuildQName function, where integer overflows in buffer size calculations can lead to a stack-based buffer overflow. This issue can result in memory corruption or a denial of service when processing crafted input.
NVD claims a severity of 7.5 High (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Fixed by applying https://gitlab.gnome.org/GNOME/libxml2/-/commit/17d950ae
CVE-2025-6170
A flaw was found in the interactive shell of the xmllint command-line tool, used for parsing XML files. When a user inputs an overly long command, the program does not check the input size properly, which can cause it to crash. This issue might allow attackers to run harmful code in rare configurations without modern protections.
NVD claims a severity of 2.5 Low (CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L)
Fixed by applying https://gitlab.gnome.org/GNOME/libxml2/-/commit/5e9ec5c1
CVE-2025-49794
A use-after-free vulnerability was found in libxml2. This issue occurs when parsing XPath elements under certain circumstances when the XML schematron has the <sch:name path="..."/> schema elements. This flaw allows a malicious actor to craft a malicious XML document used as input for libxml, resulting in the program's crash using libxml or other possible undefined behaviors.
NVD claims a severity of 9.1 Critical (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H)
Fixed by applying https://gitlab.gnome.org/GNOME/libxml2/-/commit/81cef8c5
CVE-2025-49795
A NULL pointer dereference vulnerability was found in libxml2 when processing XPath XML expressions. This flaw allows an attacker to craft a malicious XML input to libxml2, leading to a denial of service.
NVD claims a severity of 7.5 High (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Fixed by applying https://gitlab.gnome.org/GNOME/libxml2/-/commit/62048278
CVE-2025-49796
A vulnerability was found in libxml2. Processing certain sch:name elements from the input XML file can trigger a memory corruption issue. This flaw allows an attacker to craft a malicious XML input file that can lead libxml to crash, resulting in a denial of service or other possible undefined behavior due to sensitive data being corrupted in memory.
NVD claims a severity of 9.1 Critical (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H)
Fixed by applying https://gitlab.gnome.org/GNOME/libxml2/-/commit/81cef8c5
Affected Versions
- Nokogiri < 1.18.9 when using CRuby (MRI) with vendored libxml2
Patched Versions
- Nokogiri >= 1.18.9
Mitigation
Upgrade to Nokogiri v1.18.9 or later.
Users who are unable to upgrade Nokogiri may also choose a more complicated mitigation: compile and link Nokogiri against patched external libxml2 libraries which will also address these same issues.
References
Impact
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is GHSA-353F-X4GH-CQQ8? GHSA-353F-X4GH-CQQ8 is a critical-severity security vulnerability in nokogiri (rubygems), affecting versions < 1.18.9. It is fixed in 1.18.9.
- Which versions of nokogiri are affected by GHSA-353F-X4GH-CQQ8? nokogiri (rubygems) versions < 1.18.9 is affected.
- Is there a fix for GHSA-353F-X4GH-CQQ8? Yes. GHSA-353F-X4GH-CQQ8 is fixed in 1.18.9. Upgrade to this version or later.
- Is GHSA-353F-X4GH-CQQ8 exploitable, and should I be worried? Whether GHSA-353F-X4GH-CQQ8 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-353F-X4GH-CQQ8 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-353F-X4GH-CQQ8? Upgrade
nokogirito 1.18.9 or later.