Nokogiri: Possible Use-After-Free when `Nokogiri::XML::Document#encoding=` raises an exception
CVE-2026-57236 is fixed in ruby-nokogiri on 1 platform by DEBIAN-CVE-2026-57236 (version 1.19.4+dfsg-1), released July 3, 2026. It is not reported as exploited. Patch Radar priority: High.
Nokogiri is an open source XML and HTML library for the Ruby programming language. Prior to 1.19.4, calling Document#encoding= with an invalid encoding (e.g., a non-string, or a string containing a null byte) raises an exception, but only after freeing the document's current encoding string without replacing it. The document is left referencing freed memory, so the next call to Document#encoding reads invalid memory, which can cause a segfault or leak freed bytes into a Ruby String. Affects the CRuby (libxml2) implementation only; JRuby is not affected. This vulnerability is fixed in 1.19.4.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| ruby-nokogiri · Debian 14 | 1.19.4+dfsg-1 | DEBIAN-CVE-2026-57236 | Jul 3, 2026 |
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