> CVE-2026-21386 [MEDIUM]

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PUBLISHED
2026-03-16 15:16
MODIFIED
2026-03-16 15:16
CVSS_SCORE V3
4.3
EPSS (Prob. Exploit)
0.19%
Top 91.2%
DATA SOURCES:
NVD 🔗 2026-03-16 CWE MITRE 🔗 2026-11-01 FIRST EPSS 🔗 2026-11-08 GITHUB 🔗 2026-10-28 OSV 🔗 2026-11-08

> DESCRIPTION

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to use consistent error responses when handling the /mute command which allows an authenticated team member to enumerate private channels they are not authorized to know about via differing error messages for nonexistent versus private channels. Mattermost Advisory ID: MMSA-2026-00588

> 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:L/UI:N/S:U/C:L/I:N/A:N
EXPLOITABILITY
2.8
IMPACT
1.4

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/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
Low (L)
Authentifié avec compte utilisateur basique
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
None (N)
Aucune modification de données possible
A (Impact Disponibilité)
Availability Impact
None (N)
Aucune interruption de service

> RÉSUMÉ DES IMPACTS

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

> WEAKNESSES

CWE-203

> CWE DETAILED DESCRIPTIONS

CWE-203: Observable Discrepancy - The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.

> GITHUB SECURITY ADVISORY

GHSA-5mr9-crcg-8wh2 MODERATE

Mattermost fails to use consistent error responses when handling the /mute command

AFFECTED PACKAGES:
GO / github.com/mattermost/mattermost-server
>= 11.3.0-rc1, < 11.3.1
Fixed in: 11.3.1
GO / github.com/mattermost/mattermost-server
>= 11.2.0-rc1, < 11.2.3
Fixed in: 11.2.3
GO / github.com/mattermost/mattermost-server
>= 10.11.0-rc1, < 10.11.11
Fixed in: 10.11.11
GO / github.com/mattermost/mattermost-server
< 5.3.2-0.20260130144323-5bb5261c72fa
Fixed in: 5.3.2-0.20260130144323-5bb5261c72fa
GO / github.com/mattermost/mattermost/server/v8
< 8.0.0-20260130144323-5bb5261c72fa
Fixed in: 8.0.0-20260130144323-5bb5261c72fa

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

Private channel enumeration via /mute slash command

AFFECTED PACKAGES:
Unknown / Unknown
30 versions affected
ALIASES:
GHSA-5mr9-crcg-8wh2, GO-2026-4744

> HISTORIQUE DES MODIFICATIONS

Première apparition
16/03/2026 15:16
Source: NVD
📊 ENRICHISSEMENT 01/06/2026 06:01
CWE
Champ modifié: Description CWE
Ancienne valeur:
CWE-203: Observable Discrepancy - The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor, which exposes securit...
Nouvelle valeur:
CWE-203: Observable Discrepancy - The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.
📊 ENRICHISSEMENT 01/04/2026 06:02
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-203: Observable Discrepancy - The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor, which exposes securit...
Total des modifications: 2 Dernière mise à jour: 5 months ago

> REFERENCES

https://mattermost.com/security-updates
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