Answer in brief
CVE-2026-126209 records a Medium severity (CVSS 5.3) vulnerability in Loofah allowed_uri? treats javascript: alert(1) as safe. The current sources do not mark it as known exploited. The current feed maps flavorjones/loofah (generic), loofah (rubygems). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps flavorjones/loofah (generic), loofah (rubygems). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| flavorjones/loofahgeneric | >=2.25.0 <2.25.3 | 2.25.3 |
| loofahrubygems | >=2.25.0,<2.25.3 | 2.25.3 |
Published upstream
Nov 12, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 12, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 12, 2026
Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. From 2.25.0 until 2.25.3, Loofah::HTML5::Scrub.allowed_uri? strips whitespace and control characters before decoding a semicolon-less numeric character reference, changing where the reference ends and hiding a javascript: or vbscript: scheme that a browser reconstructs. The bypass applies to encoded colons and encoded scheme letters when a stripped character terminates the numeric reference. An application that renders the approved value in href or another browser-interpreted URI attribute can allow cross-site scripting, and Rails::HTML::Sanitizer.allowed_uri? re-exports the affected helper. Loofah's default sanitize() path is not affected because Nokogiri decodes entities before URI evaluation. This issue is fixed in version 2.25.3.
Quoted source text, attributed separately from HOL analysis.