CVE-2026-33979

Published Mar 27, 2026

Last updated 5 months ago

Overview

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.
Source
security-advisories@github.com
NVD status
Analyzed
Products
express_xss_sanitizer

Risk scores

CVSS 3.1

Type
Secondary
Base score
8.2
Impact score
4.2
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
Severity
HIGH

Weaknesses

security-advisories@github.com
CWE-79

Social media

Hype score
Not currently trending

Configurations