Nokogiri XSLT transform has a memory leak

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS

• CVE-2026-79771: 0.42% estimated exploitation activity in the next 30 days; percentile 36.63 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Nokogiri's Nokogiri::XSLT::Stylesheet#transform leaks a small heap allocation when passed a Ruby string parameter containing a null byte. For applications that pass attacker-controlled input through XSLT.transform parameters, this may be a vector for a denial of service attack against long-running processes. Mitigation Upgrade to Nokogiri = 1.19.3. Users may also be able to mitigate this issue without upgrading by validating untrusted transform parameters before passing them to Nokogiri::XSLT::Stylesheet#transform. Severity The Nokogiri maintainers have evaluated this as Moderate Severity, CVSS 5.3. Each leaked allocation is approximately 24–32 bytes, so meaningful memory growth requires sustained attacker-controlled traffic at high call rates. The bug does not cause memory corruption, information disclosure, or any change in the behavior of the transform itself, and the string-handling exception is raised as expected. Applications that do not pass raw attacker-controlled…

Published by the source

6 May 2026, 18:27 UTC

Last modified by the source

2 Sep 2026, 14:43 UTC

Source last checked

26 Oct 2026, 15:52 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-v2fc-qm4h-8hqv

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# Patch Next advisory brief: CVE-2026-79771

Advisory: Nokogiri XSLT transform has a memory leak
IDs: CVE-2026-79771, GHSA-v2fc-qm4h-8hqv
Record: https://patchnext.com/advisories/cve-2026-79771 (revision 1, source checked 26 Oct 2026, 15:52 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: nokogiri 1.19.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- RubyGems nokogiri: affected < 1.19.3; fixed in 1.19.3

## Suggested inspection (read-only)
- RubyGems nokogiri: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on nokogiri.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-v2fc-qm4h-8hqv (GitHub-reviewed advisory GHSA-v2fc-qm4h-8hqv lists affected ranges: RubyGems nokogiri >=0 <1.19.3)

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