Vulnerability Description
ApostropheCMS is an open-source Node.js content management system. Versions 4.28.0 and prior contain a stored cross-site scripting vulnerability in the @apostrophecms/color-field module, where color values prefixed with -- bypass TinyColor validation intended for CSS custom properties, and the launder.string() call performs only type coercion without stripping HTML metacharacters. These unsanitized values are then concatenated directly into <style> tags both in per-widget style elements rendered for all visitors and in the global stylesheet rendered for editors, with the output marked as safe HTML. An editor can inject a value which closes the style tag and executes arbitrary JavaScript in the browser of every visitor to any page containing the affected widget. This enables mass session hijacking, cookie theft, and privilege escalation to administrative control if an admin views draft content. This issue has been fixed in version 4.29.0.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Apostrophecms | Apostrophecms | < 4.29.0 |
Related Weaknesses (CWE)
References
- https://github.com/apostrophecms/apostrophe/commit/6a89bdb7acdb2e1e9bf1429961a6bPatch
- https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-97v6-998m-fExploitMitigationVendor Advisory
- https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-97v6-998m-fExploitMitigationVendor Advisory
FAQ
What is CVE-2026-33889?
CVE-2026-33889 is a vulnerability with a CVSS score of 5.4 (MEDIUM). ApostropheCMS is an open-source Node.js content management system. Versions 4.28.0 and prior contain a stored cross-site scripting vulnerability in the @apostrophecms/color-field module, where color v...
How severe is CVE-2026-33889?
CVE-2026-33889 has been rated MEDIUM with a CVSS base score of 5.4/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-33889?
Check the references section above for vendor advisories and patch information. Affected products include: Apostrophecms Apostrophecms.