Medium (5.4) in mattermost mattermost. EPSS 0.3% chance of exploitation in the next 30 days.
Mattermost versions 9.8.0, 9.7.x <= 9.7.4, 9.6.x <= 9.6.2 and 9.5.x <= 9.5.5 fail to prevent users from specifying a RemoteId for their posts which allows an attacker to specify both a remoteId and the post ID, resulting in creating a post with a user-defined post ID. This can cause some broken functionality in the channel or thread with user-defined posts
Severity
CVSS 3.1
5.4 medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
EPSS
0.3% chance of exploitation in the next 30 days; higher than 20% of CVEs (scores of 2026-10-31)