Nokogiri: Possible Use-After-Free when setting an attribute value via `Nokogiri::XML::Attr#value=` or `#content=` (CVE-2026-57435) | HOL Guard CVE

High · CVSS 7.5CVE-2026-57435GHSA-PHWJ-RPRQ-35PP

Nokogiri: Possible Use-After-Free when setting an attribute value via `Nokogiri::XML::Attr#value=` or `#content=`

Answer in brief

CVE-2026-57435 records a High severity (CVSS 7.5) vulnerability in Nokogiri: Possible Use-After-Free when setting an attribute value via `Nokogiri::XML::Attr#value=` or `#content=`. The current sources do not mark it as known exploited. The current feed maps nokogiri (rubygems), nokogiri (rubygems). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jun 19, 2026Updated Sep 10, 2026Source checked Sep 10, 2026First seen by HOL Jun 19, 2026Material review Sep 10, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps nokogiri (rubygems), nokogiri (rubygems). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
nokogirirubygems	<1.19.4	1.19.4
nokogirirubygems	>=0 <1.19.4	1.19.4

Recommended response

Check inventory. Check lockfiles and deployed manifests for nokogiri, nokogiri.
Review the reported fix. Update nokogiri to 1.19.4; nokogiri to 1.19.4 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Jun 19, 2026
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Jun 19, 2026

Sources and claim methodology

Upstream source description

### Summary Nokogiri’s CRuby native extension could leave a Ruby wrapper pointing to freed memory when replacing the value of an XML attribute. If Ruby code had already accessed an attribute child node, `Nokogiri::XML::Attr#value=` could free the underlying native child node while the wrapper remained reachable through the document node cache. A later use of the freed child node or a Ruby GC mark could dereference an invalid pointer, causing an invalid read and a possible segfault. Nokogiri 1.19.4 preserves any 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 attribute's child node and then replace that same attribute's value via `Attr#value=` or `#content=`. Nokogiri 1.19.4 makes this pattern safe with no change to the public API. Already-wrapped attribute child nodes are preserved before the value is replaced. ### Mitigation Upgrade to Nokogiri 1.19.4 or later. As a workaround, avoid accessing attribute child nodes directly via `Attr#child` or similar before mutating the same attribute’s value. ### Credit This issue was responsibly reported by Zheng Yu from depthfirst.com.

Quoted source text, attributed separately from HOL analysis.