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

CVE-2026-57435 is fixed in ruby-nokogiri on 1 platform by DEBIAN-CVE-2026-57435 (version 1.19.4+dfsg-1), released July 3, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-57435
- Priority: High
- CVSS: 7.5 (Important)
- EPSS: 0.0046
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 25, 2026
- Weakness: Use After Free
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-57435

## Description

Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, 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. This vulnerability is fixed in 1.19.4.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | ruby-nokogiri Debian 14 | 1.19.4+dfsg-1 | [DEBIAN-CVE-2026-57435](https://patchblox.com/security/data/fix/linux/debian-cve-2026-57435.md) | Jul 3, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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