Vulnerability Description
Express XSS Sanitizer is Express 4.x and 5.x middleware which sanitizes user input data (in req.body, req.query, req.headers and req.params) to prevent Cross Site Scripting (XSS) attack. A vulnerability has been identified in versions prior to 2.0.2 where restrictive sanitization configurations are silently ignored. In version 2.0.2, the validation logic has been updated to respect explicitly provided empty configurations. Now, if allowedTags or allowedAttributes are provided (even if empty), they are passed directly to sanitize-html without being overridden.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Express Xss Sanitizer Project | Express Xss Sanitizer | < 2.0.2 |
Related Weaknesses (CWE)
References
- https://github.com/AhmedAdelFahim/express-xss-sanitizer/commit/5623009ef11dcf095Patch
- https://github.com/AhmedAdelFahim/express-xss-sanitizer/releases/tag/v2.0.2ProductRelease Notes
- https://github.com/AhmedAdelFahim/express-xss-sanitizer/security/advisories/GHSAExploitMitigationVendor Advisory
FAQ
What is CVE-2026-33979?
CVE-2026-33979 is a vulnerability with a CVSS score of 8.2 (HIGH). Express XSS Sanitizer is Express 4.x and 5.x middleware which sanitizes user input data (in req.body, req.query, req.headers and req.params) to prevent Cross Site Scripting (XSS) attack. A vulnerabili...
How severe is CVE-2026-33979?
CVE-2026-33979 has been rated HIGH with a CVSS base score of 8.2/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-33979?
Check the references section above for vendor advisories and patch information. Affected products include: Express Xss Sanitizer Project Express Xss Sanitizer.