> CVE-2026-33979 [HIGH]

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PUBLISHED
2026-03-27 22:16
MODIFIED
2026-03-27 22:16
CVSS_SCORE V3
8.2
EPSS (Prob. Exploit)
0.44%
Top 62.8%
DATA SOURCES:
NVD 🔗 2026-03-27 CWE MITRE 🔗 2026-11-01 FIRST EPSS 🔗 2026-10-25 GITHUB 🔗 2026-11-05 OSV 🔗 2026-11-01

> 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.

> AFFECTED_PRODUCTS

ℹ️ Aucun produit affecté n'a encore été publié par NVD pour cette CVE.

> CVSS V3 METRICS

CVSS_VECTOR
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
EXPLOITABILITY
3.9
IMPACT
4.2

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
Métrique Valeur Interprétation
AV (Vecteur d'Attaque)
Attack Vector
Network (N)
Exploit possible à distance via réseau (HTTP, API, etc.)
AC (Complexité d'Attaque)
Attack Complexity
Low (L)
Peu de conditions requises pour exploiter
PR (Privilèges Requis)
Privileges Required
None (N)
Aucune authentification requise
UI (Interaction Utilisateur)
User Interaction
None (N)
Aucune interaction utilisateur nécessaire
S (Périmètre)
Scope
Unchanged (U)
Impact reste dans le périmètre du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
Low (L)
Divulgation limitée d'informations
I (Impact Intégrité)
Integrity Impact
High (H)
Modification totale des données possible
A (Impact Disponibilité)
Availability Impact
None (N)
Aucune interruption de service

> RÉSUMÉ DES IMPACTS

Confidentialité
Low
Divulgation limitée d'informations
Intégrité
High
Modification totale des données possible
Disponibilité
None
Aucune interruption de service

> WEAKNESSES

CWE-79 CWE-183

> CWE DETAILED DESCRIPTIONS

CWE-79: Improper Neutralization of Input During Web Page Generation - The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. | CWE-183: Permissive List of Allowed Inputs - The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are explicitly allowed by policy because the inputs are assumed to be safe, but the list is too permissive - that is, it allows an input that is unsafe, leading to resultant weaknesses.

> GITHUB SECURITY ADVISORY

GHSA-3843-rr4g-m8jq HIGH

Express XSS Sanitizer: allowedTags/allowedAttributes bypass leads to permissive sanitization (XSS risk)

AFFECTED PACKAGES:
NPM / express-xss-sanitizer
< 2.0.2
Fixed in: 2.0.2

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

Express XSS Sanitizer: allowedTags/allowedAttributes bypass leads to permissive sanitization (XSS risk)

AFFECTED PACKAGES:
Unknown / Unknown
9 versions affected
ALIASES:
GHSA-3843-rr4g-m8jq

> HISTORIQUE DES MODIFICATIONS

Première apparition
27/03/2026 22:16
Source: NVD
📊 ENRICHISSEMENT 01/11/2026 06:59
CWE
Champ modifié: Description CWE
Ancienne valeur:
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') - The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in...
Nouvelle valeur:
CWE-79: Improper Neutralization of Input During Web Page Generation - The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a...
📊 ENRICHISSEMENT 01/04/2026 06:02
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') - The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in...
Total des modifications: 2 Dernière mise à jour: 1 week ago

> REFERENCES

https://github.com/AhmedAdelFahim/express-xss-sanitizer/commit/5623009ef11dcf095...
https://github.com/AhmedAdelFahim/express-xss-sanitizer/releases/tag/v2.0.2
https://github.com/AhmedAdelFahim/express-xss-sanitizer/security/advisories/GHSA...
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