Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11, 10.12.x <= 10.12.0 fail to validate the relationship between the post being updated and the MSTeams plugin OAuth flow which allows an attacker to edit arbitrary posts via a crafted MSTeams plugin OAuth redirect URL.
Fix
Patch, vendor advisory and mitigation references on NVD 1
- https://mattermost.com/security-updates Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 5.3 · mattermostNVD modified 2026-10-19 13:10
Affected (CPE criteria) 1
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
References 1
- https://mattermost.com/security-updates Vendor Advisory