CVE-2026-33979

HIGH EPSS 30.1%
Published Mar 27, 20263mo ago · Modified Jun 17, 20262w ago
8.2 CVSS 3.1
High
Find Similar
Published Mar 27, 2026 3mo ago
Last Modified Jun 17, 2026 2w ago

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 Details

Base Score
8.2
Exploitability
3.9
Impact
4.2
Vector string
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

Threat Intelligence

EPSS Exploit Probability
30.1% percentile
Exploit & Patch Status
Public Exploit Known
Patch Available

Weaknesses 2

CWE-183
CWE-79 Cross-site Scripting Injection

Affected Products 1

VendorProductVersionRange
express_xss_sanitizer_projectexpress_xss_sanitizer* <2.0.2

References 3

  • github.com https://github.com/AhmedAdelFahim/express-xss-sanitizer/commit/5623009ef11dcf095c163a38dea07b9cc22ad19f
    Patch
  • github.com https://github.com/AhmedAdelFahim/express-xss-sanitizer/releases/tag/v2.0.2
    ProductRelease Notes
  • github.com https://github.com/AhmedAdelFahim/express-xss-sanitizer/security/advisories/GHSA-3843-rr4g-m8jq
    ExploitMitigationVendor Advisory

Remediation

  • github.com https://github.com/AhmedAdelFahim/express-xss-sanitizer/commit/5623009ef11dcf095c163a38dea07b9cc22ad19f
    Patch