Auth bypass in Mattermost

CVE-2025-27715

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.

Vulnerability class: Broken Access Control

EPSS: 0.002 (10.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 3.3 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:N.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-27715?
CVE-2025-27715 is a low-severity vulnerability in Mattermost, classified under Incorrect Authorization. CVSS score: 3.3/10. Published 2025-03-21.
How severe is CVE-2025-27715?
Low severity. CVSS v3 base score is 3.3 out of 10.