CVE-2026-33979 (GCVE-0-2026-33979)
Vulnerability from cvelistv5 – Published: 2026-03-27 21:29 – Updated: 2026-03-31 14:29
VLAI
EPSS
VEX
Title
Express XSS Sanitizer: allowedTags/allowedAttributes bypass leads to permissive sanitization (XSS risk)
Summary
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.
Severity
8.2 (High)
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-31 14:29 UTC
CWE
Assigner
GitHub_M
CNA
References
3 references
| URL | Tags |
|---|---|
| https://github.com/AhmedAdelFahim/express-xss-san… | x_refsource_CONFIRM |
| https://github.com/AhmedAdelFahim/express-xss-san… | x_refsource_MISC |
| https://github.com/AhmedAdelFahim/express-xss-san… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| AhmedAdelFahim | express-xss-sanitizer |
Affected:
< 2.0.2
|
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Browse all ATT&CK techniques and the vulnerabilities related to each.
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