Mattermost versions 10.5.x <= 10.5.1, 10.4.x <= 10.4.3, 9.11.x <= 9.11.9 fail to check the "Allow Users to View Archived Channels" configuration when fetching channel metadata of a post from archived channels, which allows authenticated users to access such information when a channel is archived.
CVE ID: CVE-2025-27571
CVSS Base Severity: MEDIUM
CVSS Base Score: 4.3
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Vendor: Mattermost
Product: Mattermost
EPSS Score: 0.03% (probability of being exploited)
EPSS Percentile: 5.27% (scored less or equal to compared to others)
EPSS Date: 2025-04-18 (when was this score calculated)