CVE-2026-21386mediumCWE-203

CVE-2026-21386: falha de média gravidade em Mattermost

Private channel enumeration via /mute slash command

Publicada em

Seguir esta CVE+ Monitorar Mattermost+ Monitorar github.com/mattermost/mattermost-server

Aviso por e-mail quando ela entrar no KEV, ganhar PoC pública ou subir de nota.

13Vexday Risk Score

Sem sinal de exploração. Nenhum artefato público de exploração conhecido até agora.

ssvc Trackcvss 4.3epss 0.2%
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
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Produtos afetados
Mattermost · Mattermost
CVEs relacionadas — Mattermost

No mesmo produto, das mais perigosas para as menos.

CVE-2025-25279CRITICALArbitrary file read in Mattermost Boards via import & export board archiveEPSS 24.2%CVE-2021-37859HIGHReflected XSS in OAuth FlowEPSS 3.3%CVE-2022-3257LOWServer-side Denial of Service while processing a specifically crafted GIF fileEPSS 1.3%CVE-2022-4044MEDIUMAuthenticated user could send multiple requests containing a large Auto Responder Message payload and can crash a Mattermost serverEPSS 1.1%CVE-2022-3147LOWServer-side Denial of Service while processing a specifically crafted JPEG fileEPSS 1.1%CVE-2025-4981CRITICALPath Traversal Leading to RCE by Any Authenticated Mattermost UserEPSS 1.0%