# CVE-2026-126207: Loofah: CSS url() sanitization bypass via escaped parentheses

Status: published. Published: 2026-11-12. Updated: 2026-11-12.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- flavorjones / loofah: < 2.25.3 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 4.7 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-180, CWE-184

## 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-5767 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/flavorjones/loofah/pull/324 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/flavorjones/loofah/commit/b198a36e44c9c5408163ac50787825e8ca0b166b (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/flavorjones/loofah/releases/tag/v2.25.3 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-126207; retrieved 2026-11-12; source updated 2026-11-12

Revision: ce32fceaa44b7b7d4d7cbe2376709a9df89e0dd7a2e8ac5b2f5947e770052035

Canonical: https://y2.dev/cve/CVE-2026-126207

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