CVE-2025-0503: Mattermost Server

Medium severity, CVSS 5.3. EPSS: 0.3% chance of exploitation in the next 30 days.

Mattermost versions 9.11.x <= 9.11.6 fail to filter out DMs from the deleted channels endpoint which allows an attacker to infer user IDs and other metadata from deleted DMs if someone had manually marked DMs as deleted in the database.

Affected products

• Mattermost Mattermost Server: from 9.11.0, before 9.11.7 (fixed in 9.11.7)

Published 2025-02-14. Last modified 2026-06-17.