CVE-2026-126205
Loofah: Regular expression denial of service in the SVG local-reference check
Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. Prior to 2.25.3, the Loofah HTML5 sanitizer checks href and xlink:href on elements in SVG_ALLOW_LOCAL_HREF with a regular expression whose line anchor and newline-matching whitespace cause an all-whitespace value to be rescanned from every line start. An attacker can submit an SVG reference element with a long multiline-whitespace attribute and consume CPU quadratically during sanitization. CRuby 3.1 and earlier and JRuby are affected, while CRuby 3.2 and later uses linear-time regular-expression matching. The default safelist reaches the vulnerable check without a configuration change. This issue is fixed in version 2.25.3.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| loofah flavorjones |
< 2.25.3 (affected) | CNA: GitHub_M |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 5.3 medium |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L | CNA: GitHub_M |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/flavorjones/loofah/security/advisories/GHSA-mf2j-8f84-cc9qCNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/flavorjones/loofah/pull/324CNA: GitHub_M · x_refsource_MISC
- https://github.com/flavorjones/loofah/commit/2f31e7fae36036c9882d3d0fae720e1014c57cd1CNA: GitHub_M · x_refsource_MISC
- https://github.com/flavorjones/loofah/releases/tag/v2.25.3CNA: GitHub_M · x_refsource_MISC
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