Auth bypass in Mattermost

CVE-2025-10545

Mattermost versions 10.5.x <= 10.5.10, 10.11.x <= 10.11.2 fail to properly validate guest user permissions when adding channel members which allows guest users to add any team members to their private channels via the `/api/v4/channels/{channel_id}/members` endpoint

Vulnerability class: Broken Access Control

Published · last modified .

CVSS v3 metric

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

EPSS exploit prediction

EPSS: 0.003 (23.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 23rd percentile — 23.2% 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-2025-10545: 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-2025-10545?
CVE-2025-10545 is a low-severity vulnerability in Mattermost, classified under Incorrect Authorization. CVSS score: 3.1/10. Published 2025-10-16.
How severe is CVE-2025-10545?
Low severity. CVSS v3 base score is 3.1 out of 10.