CVE-2026-5163

Mattermost versions 11.5.x <= 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite endpoint.. Mattermost Advisory ID: MMSA-2026-00645

Score
CVSS 3.1 6.5 Medium
Status
Analyzed - responsibledisclosure@mattermost.com
Published
2026-05-18
Last modified
2026-10-14
Weaknesses
CWE-862

Affected products

References

 
 
© AVABIS GmbH privacypolicy about