Medium (4.3) in mattermost mattermost server. EPSS 0.3% chance of exploitation in the next 30 days.
Mattermost versions 9.10.x <= 9.10.2, 9.11.x <= 9.11.1, 9.5.x <= 9.5.9 and 10.0.x <= 10.0.0 fail to properly authorize the requests to /api/v4/channels which allows a User or System Manager, with "Read Groups" permission but with no access for channels to retrieve details about private channels that they were not a member of by sending a request to /api/v4/channels.
Severity
CVSS 3.1
4.3 medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
EPSS
0.3% chance of exploitation in the next 30 days; higher than 21% of CVEs (scores of 2026-10-31)