Auth bypass in Mattermost

CVE-2025-27571

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.

Vulnerability class: Broken Access Control

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.003 (17.0th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 17th percentile — 17.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-27571: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-27571?
CVE-2025-27571 is a medium-severity vulnerability in Mattermost, classified under Incorrect Authorization. CVSS score: 4.3/10. Published 2025-04-16.
How severe is CVE-2025-27571?
Medium severity. CVSS v3 base score is 4.3 out of 10.