# CVE-2026-116695: Crass: Incorrect tokenization of bad URLs enables CSS sanitizer bypass

Status: published. Published: 2026-10-27. Updated: 2026-11-03.

Crass is a Ruby CSS parser that is compliant with the CSS Syntax Level 3 specification. Prior to 1.0.8, Crass incorrectly treats a closing parenthesis after an escaped backslash as escaped while consuming the remnants of a bad URL. Crass therefore keeps declarations, style rules, or at-rules inside a bad URL token even though a browser treats them as live CSS. A sanitizer that parses untrusted CSS with Crass and reserializes it without rejecting the bad URL can allow CSS used for UI redress, external resource loading, or CSS-based data exfiltration, but this issue does not enable script execution in modern browsers. This issue is fixed in version 1.0.8.

## Remediation

- fix: crass (RubyGems): OSV reports a fixed version 1.0.8. Check the advisory for supported release branches. (source: OSV GHSA-pq4g-8rxf-4g29) — https://github.com/advisories/GHSA-pq4g-8rxf-4g29

## Affected products and versions

- rgrove / crass: < 1.0.8 (affected). Source: CNA: GitHub_M
-  / crass (crass): 0.0.1 (affected, RubyGems); 0.0.2 (affected, RubyGems); 0.1.0 (affected, RubyGems); 0.2.0 (affected, RubyGems); 0.2.1 (affected, RubyGems); 1.0.0 (affected, RubyGems); 1.0.1 (affected, RubyGems); 1.0.2 (affected, RubyGems); 1.0.3 (affected, RubyGems); 1.0.4 (affected, RubyGems); 1.0.5 (affected, RubyGems); 1.0.6 (affected, RubyGems); 1.0.7 (affected, RubyGems); Ecosystem version events: introduced 0; fixed 1.0.8. Source: OSV GHSA-pq4g-8rxf-4g29

## Severity and prioritization

- CVSS 4.0: 5.3 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: 0.35% as of 2026-11-02; percentile 29.03%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-436

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/rgrove/crass/security/advisories/GHSA-pq4g-8rxf-4g29 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/rgrove/crass/commit/689fc45c632fdf3803b2f4e844ffc9cca3b08f34 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/rgrove/crass/releases/tag/v1.0.8 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/advisories/GHSA-pq4g-8rxf-4g29 (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-pq4g-8rxf-4g29 (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-116695; retrieved 2026-11-03; source updated 2026-11-03

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-pq4g-8rxf-4g29; retrieved 2026-11-03; source updated 2026-10-28

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-116695; retrieved 2026-11-03; source updated Not reported

Revision: 094e3308fa7822c4d9c23d8d621c82dcfee496bbe85033f1fee2ca881754b595

Canonical: https://y2.dev/cve/CVE-2026-116695

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