| Package | Affected versions | Patched versions |
|---|---|---|
| github.com/mattermost/mattermost-server | ≥ 11.5.0+incompatible, < 11.5.2+incompatible< 5.3.2-0.20260401090745-f4d1abe7e8f5 | 11.5.2+incompatible5.3.2-0.20260401090745-f4d1abe7e8f5 |
| github.com/mattermost/mattermost-server/v5 | all versions | |
| github.com/mattermost/mattermost-server/v6 | all versions | |
| github.com/mattermost/mattermost/server/v8 | ≥ 11.5.0, < 11.5.2< 8.0.0-20260401090745-f4d1abe7e8f5 | 11.5.28.0.0-20260401090745-f4d1abe7e8f5 |
| mattermost server | ≥ 11.5.0, < 11.5.2 | 11.5.2 |
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
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