Nokogiri: Use-After-Free in Nokogiri when replacing an attribute value

Exploitation

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

CVSS 4.0

2.0 · CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary Nokogiri's CRuby native extension could leave a Ruby wrapper pointing to freed memory when replacing the value of an existing XML attribute via `Nokogiri::XML::Node#[]=` or `Nokogiri::XML::Node#lang=`. If Ruby code had already accessed the attribute's child nodes, replacing the value could free those native child nodes while their wrappers remained reachable. Using one of those child nodes afterwards could cause an invalid read and a possible segfault. This is the same class of issue as GHSA-phwj-rprq-35pp, which was fixed for `Attr#value=` in Nokogiri 1.19.4. Nokogiri 1.19.5 preserves all already-wrapped attribute child nodes before replacing the attribute value. JRuby is not affected.

Severity The Nokogiri maintainers have evaluated this as low severity. Reaching it requires an unusual API-usage pattern that does not arise during normal use. The application must directly access an…

Published by the source

10 Nov 2026, 20:51 UTC

Last modified by the source

10 Nov 2026, 21:00 UTC

Source last checked

11 Nov 2026, 07:35 UTC

1. Revision 2 · amended · 11 Nov 2026

   Amended from osv record GHSA-3w22-6jfg-527w

2. Revision 1 · created · 10 Nov 2026

   Published from ghsa record GHSA-3w22-6jfg-527w

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# Patch Next advisory brief: CVE-2026-126064

Advisory: Nokogiri: Use-After-Free in Nokogiri when replacing an attribute value
IDs: CVE-2026-126064, GHSA-3w22-6jfg-527w
Record: https://patchnext.com/advisories/cve-2026-126064 (revision 2, source checked 11 Nov 2026, 07:35 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: nokogiri 1.19.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- RubyGems nokogiri: affected < 1.19.5; fixed in 1.19.5

## 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-3w22-6jfg-527w (GitHub-reviewed advisory GHSA-3w22-6jfg-527w lists affected ranges: RubyGems nokogiri >=0 <1.19.5)
- Verified: https://osv.dev/vulnerability/GHSA-3w22-6jfg-527w (OSV record GHSA-3w22-6jfg-527w lists affected ranges: RubyGems nokogiri >=0 <1.19.5 (fixed))

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