CVE-2026-33979
Express XSS Sanitizer: allowedTags/allowedAttributes bypass leads to permissive sanitization (XSS risk)
CVSS Score
8.2
EPSS Score
0.0%
EPSS Percentile
1th
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.
| CWE | CWE-183 CWE-79 |
| Vendor | ahmedadelfahim |
| Product | express-xss-sanitizer |
| Published | Mar 27, 2026 |
| Last Updated | Mar 31, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
High
Availability
None
Affected Versions
AhmedAdelFahim / express-xss-sanitizer
< 2.0.2
References
github.com: https://github.com/AhmedAdelFahim/express-xss-sanitizer/security/advisories/GHSA-3843-rr4g-m8jq github.com: https://github.com/AhmedAdelFahim/express-xss-sanitizer/commit/5623009ef11dcf095c163a38dea07b9cc22ad19f github.com: https://github.com/AhmedAdelFahim/express-xss-sanitizer/releases/tag/v2.0.2