CVSS 3.1
5.3 mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:LCVE-2026-126205
Loofah: Regular expression denial of service in the SVG local-reference check
Medium (5.3) in flavorjones loofah. Fixed in loofah 2.25.3.
On this page
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.
Severity
- Published
- Modified
- Assigned by
- GitHub_M (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
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Affected
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| flavorjones loofah | < 2.25.3 |
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-mf2j-8f84-cc9q | RubyGems | loofah | <2.25.3 | 2.25.3 |
Attack patterns (CAPEC)
- CAPEC-492 Regular Expression Exponential Blowup
- CAPEC-147 XML Ping of the Death Likelihood: Low · Severity: Medium
- CAPEC-227 Sustained Client Engagement
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.