CVE-2026-126207
Loofah: CSS url() sanitization bypass via escaped parentheses
Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. Prior to 2.25.3, Loofah::HTML5::Scrub.scrub_css checks only the first parse of a style attribute, then rebuilds CSS with identifier escapes decoded so escaped parentheses, property names, comments, or quotes can become a live url() without a second safety check. An attacker can use list-style to make a viewer's browser request an attacker-chosen URL when content renders, or cursor to make the request on hover. The request can disclose the viewer's IP address, user agent, access timing, and access to internal-network hosts, but no script survives sanitization and the attacker cannot read the response. 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 / 4.7 medium |
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N | 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-m3x9-938q-5767CNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/flavorjones/loofah/pull/324CNA: GitHub_M · x_refsource_MISC
- https://github.com/flavorjones/loofah/commit/b198a36e44c9c5408163ac50787825e8ca0b166bCNA: GitHub_M · x_refsource_MISC
- https://github.com/flavorjones/loofah/releases/tag/v2.25.3CNA: GitHub_M · x_refsource_MISC
For agents and automation
Read public disclosures for free as Markdown or JSON. Compatible browsers also expose native WebMCP tools to search disclosures, read this page, and discover API access.
Use the ontology-linked Cyber API with x402 pay per request, or a Y2 Pro or Elite API key with the intel:cyber scope.
Endpoints and access details
https://api.y2.dev/api/v2/cyber/cveshttps://api.y2.dev/api/v2/cyber/cves/{cveId}
A workspace owner or admin can create a Pro or Elite API key. Send Authorization: Bearer <Y2_API_KEY> from your trusted agent runtime.
For x402, omit Authorization and read the HTTP 402 payment challenge before signing a retry. Public browser tools do not make payments.