CVE-2026-20796

LOW

Mattermost <10.11.9 - Info Disclosure

Title source: llm
STIX 2.1

Description

Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549

Scores

CVSS v3 3.1
EPSS 0.0001
EPSS Percentile 1.3%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-367
Status published
Products (2)
mattermost/mattermost-server 10.11.0 - 10.11.10Go
mattermost/mattermost_server 10.11.0 - 10.11.10
Published Feb 13, 2026
Tracked Since Feb 18, 2026