CVE-2026-116695
Crass: Incorrect tokenization of bad URLs enables CSS sanitizer bypass
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.
Fixes and workarounds
Fix
crass (RubyGems): OSV reports a fixed version 1.0.8. Check the advisory for supported release branches.
Source: OSV GHSA-pq4g-8rxf-4g29Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| crass rgrove |
< 1.0.8 (affected) | CNA: GitHub_M |
crasscrass
RubyGems |
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 events (ECOSYSTEM)Other versions: unaffected |
OSV GHSA-pq4g-8rxf-4g29 |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 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 | CNA: GitHub_M |
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-4g29CNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/rgrove/crass/commit/689fc45c632fdf3803b2f4e844ffc9cca3b08f34CNA: GitHub_M · x_refsource_MISC
- https://github.com/rgrove/crass/releases/tag/v1.0.8CNA: GitHub_M · x_refsource_MISC
- https://github.com/advisories/GHSA-pq4g-8rxf-4g29OSV / GitHub Security Advisories · advisory
- https://osv.dev/vulnerability/GHSA-pq4g-8rxf-4g29OSV / GitHub Security Advisories · osv
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