CVE-2026-33979Express XSS Sanitizer: allowedTags/allowedAttributes bypass leads to permissive sanitization (XSS risk)
Updated under an hour ago ()
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It affects AhmedAdelFahim express-xss-sanitizer and 1 other product. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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
- 8.2 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
- Weakness (CWE)
- CWE-183, CWE-79
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Analyzed
- Record last updated
- Mar 31, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
AhmedAdelFahim express-xss-sanitizer ahmedadelfahim:express_xss_sanitizer (from the name) | before 2.0.2 | CNA record |
express_xss_sanitizer_project express_xss_sanitizer express_xss_sanitizer_project:express_xss_sanitizer | before 2.0.2 | NVD |
References
- https://github.com/AhmedAdelFahim/express-xss-sanitizer/security/advisories/GHSA-3843-rr4g-m8jqx-refsource-confirm, exploit, mitigation, vendor-advisory
- https://github.com/AhmedAdelFahim/express-xss-sanitizer/commit/5623009ef11dcf095c163a38dea07b9cc22ad19fx-refsource-misc, patch
- https://github.com/AhmedAdelFahim/express-xss-sanitizer/releases/tag/v2.0.2x-refsource-misc, product, release-notes
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.