> CVE-2026-71478 [MEDIUM]

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PUBLISHED
2026-08-06 22:18
MODIFIED
2026-08-06 22:18
CVSS_SCORE V3
6.1
EPSS (Prob. Exploit)
0.36%
Top 72.0%
DATA SOURCES:
NVD 🔗 2026-08-06 CWE MITRE 🔗 2026-11-01 FIRST EPSS 🔗 2026-10-25 GITHUB 🔗 2026-10-29 OSV 🔗 2026-08-13

> DESCRIPTION

league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a javascript: URL that browsers discard before parsing the scheme, causing the browser to still execute the script even when the unsafe-link filter is enabled. This issue is fixed in 2.9.0.

> 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:R/S:C/C:L/I:L/A:N
EXPLOITABILITY
2.8
IMPACT
2.7

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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
Required (R)
Nécessite une action utilisateur (clic lien, ouverture fichier, etc.)
S (Périmètre)
Scope
Changed (C)
Impact s'étend au-delà du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
Low (L)
Divulgation limitée d'informations
I (Impact Intégrité)
Integrity Impact
Low (L)
Modification limitée des données possible
A (Impact Disponibilité)
Availability Impact
None (N)
Aucune interruption de service

> RÉSUMÉ DES IMPACTS

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

> WEAKNESSES

CWE-79 CWE-86 CWE-692

> 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-86: Improper Neutralization of Invalid Characters in Identifiers in Web Pages - The product does not neutralize or incorrectly neutralizes invalid characters or byte sequences in the middle of tag names, URI schemes, and other identifiers. | CWE-692: Incomplete Denylist to Cross-Site Scripting - The product uses a denylist-based protection mechanism to defend against XSS attacks, but the denylist is incomplete.

> GITHUB SECURITY ADVISORY

GHSA-29pj-957v-52mc MODERATE

league/commonmark: AttributesExtension href/src unsafe-link filter bypass via embedded control bytes

AFFECTED PACKAGES:
COMPOSER / league/commonmark
>= 1.5.0, <= 2.8.3
Fixed in: 2.9.0

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

league/commonmark: AttributesExtension href/src unsafe-link filter bypass via embedded control bytes

AFFECTED PACKAGES:
Unknown / Unknown
ALIASES:
GHSA-29pj-957v-52mc

> HISTORIQUE DES MODIFICATIONS

Première apparition
06/08/2026 22:18
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 01/09/2026 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: 2 days ago

> REFERENCES

https://github.com/thephpleague/commonmark/commit/493a5aa7d65754b73846006eaff9c2...
https://github.com/thephpleague/commonmark/releases/tag/2.9.0
https://github.com/thephpleague/commonmark/security/advisories/GHSA-29pj-957v-52...
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