> CVE-2026-49851 [HIGH]

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PUBLISHED
2026-06-24 18:17
MODIFIED
2026-06-24 18:17
CVSS_SCORE V3
8.7
EPSS (Prob. Exploit)
0.52%
Top 55.8%
DATA SOURCES:
NVD 🔗 2026-06-24 RED HAT 🔗 2026-06-28 CWE MITRE 🔗 2026-11-01 FIRST EPSS 🔗 2026-11-01 GITHUB 🔗 2026-11-05 OSV 🔗 2026-11-02 MSRC 🔗 2026-11-02

> DESCRIPTION

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, Mistune is vulnerable to a CPU exhaustion DoS due to superlinear (approximately O(n²)) behavior in parse_link_text. When parsing Markdown containing many consecutive [ characters, parse_link_text repeatedly scans the input using a regex search inside a loop. Each iteration re-scans a large portion of the remaining string, resulting in quadratic-time behavior. An attacker-controlled Markdown input can therefore trigger excessive CPU usage with a very small payload. This vulnerability is fixed in 3.3.0.

> AFFECTED_PRODUCTS

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

> CVSS V3 METRICS

CVSS_VECTOR
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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
None (N)
Aucune divulgation d'informations
I (Impact Intégrité)
Integrity Impact
None (N)
Aucune modification de données possible
A (Impact Disponibilité)
Availability Impact
High (H)
Interruption totale du service possible

> RÉSUMÉ DES IMPACTS

Confidentialité
None
Aucune divulgation d'informations
Intégrité
None
Aucune modification de données possible
Disponibilité
High
Interruption totale du service possible

> WEAKNESSES

CWE-400 CWE-407 CWE-770

> CWE DETAILED DESCRIPTIONS

CWE-400: Uncontrolled Resource Consumption - The product does not properly control the allocation and maintenance of a limited resource. | CWE-407: Inefficient Algorithmic Complexity - An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached. | CWE-770: Allocation of Resources Without Limits or Throttling - The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

> RED HAT SECURITY ADVISORIES

Red Hat Security Advisory: RHOAI 3.4.4 - Red Hat OpenShift AI
Updated images are now available for Red Hat OpenShift AI.

> RED HAT SEVERITY ASSESSMENT

THREAT SEVERITY
Important

> GITHUB SECURITY ADVISORY

GHSA-qcq2-496w-v96p HIGH

Mistune: Potential DoS via quadratic-time parsing in parse_link_text

AFFECTED PACKAGES:
PIP / mistune
< 3.3.0
Fixed in: 3.3.0

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

Mistune: Potential DoS via quadratic-time parsing in parse_link_text

AFFECTED PACKAGES:
Unknown / Unknown
46 versions affected
ALIASES:
GHSA-qcq2-496w-v96p, PYSEC-2026-2652

> HISTORIQUE DES MODIFICATIONS

Première apparition
24/06/2026 18:17
Source: NVD
📊 ENRICHISSEMENT 01/07/2026 06:01
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-400: Uncontrolled Resource Consumption - The product does not properly control the allocation and maintenance of a limited resource. | CWE-407: Inefficient Algorithmic Complexity - An algorithm in...
📊 ENRICHISSEMENT 28/06/2026 05:01
REDHAT
Champ modifié: Sévérité Red Hat
Ancienne valeur:
N/A
Nouvelle valeur:
{ "threat_severity": "Important", "severity_scale": null }
📊 ENRICHISSEMENT 28/06/2026 05:01
REDHAT
Champ modifié: Red Hat
Ancienne valeur:
Non
Nouvelle valeur:
Oui
Total des modifications: 3 Dernière mise à jour: 4 months ago

> REFERENCES

https://github.com/lepture/mistune/security/advisories/GHSA-qcq2-496w-v96p
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