CVE-2026-126205

Loofah: Regular expression denial of service in the SVG local-reference check

Published Nov 12, 2026 CVSS 3.1 · 5.3 Medium EPSS n/a KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-mf2j-8f84-cc9q Loofah: Regular expression denial of service in the SVG local-reference check
History
Type Values Removed Values Added
First Time appeared Flavorjones
Flavorjones loofah
Vendors & Products Flavorjones
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Type Values Removed Values Added
Description 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.
Title Loofah: Regular expression denial of service in the SVG local-reference check
Weaknesses CWE-1333
CWE-400
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Nov 12, 2026, 8:41 PM
Reserved
Nov 10, 2026, 8:07 PM
Status
Awaiting Analysis
Published
Nov 12, 2026, 9:17 PM
Modified
Nov 12, 2026, 10:09 PM