Mattermost versions 9.11.x <= 9.11.8 fail to prompt for explicit approval before adding a team admin to a private channel, which team admins to joining private channels via crafted permalink links without explicit consent from them.
CVE ID: CVE-2025-27715
CVSS Base Severity: LOW
CVSS Base Score: 3.3
CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:N
Vendor: Mattermost
Product: Mattermost
EPSS Score: 0.03% (probability of being exploited)
EPSS Percentile: 8.27% (scored less or equal to compared to others)
EPSS Date: 2025-04-18 (when was this score calculated)