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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.

PUBLISHED Reserved 2026-03-24 | Published 2026-03-27 | Updated 2026-03-31 | Assigner GitHub_M




HIGH: 8.2CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N

Problem types

CWE-183: Permissive List of Allowed Inputs

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Product status

< 2.0.2
affected

References

github.com/...itizer/security/advisories/GHSA-3843-rr4g-m8jq

github.com/...ommit/5623009ef11dcf095c163a38dea07b9cc22ad19f

github.com/...ahim/express-xss-sanitizer/releases/tag/v2.0.2

cve.org (CVE-2026-33979)

nvd.nist.gov (CVE-2026-33979)

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