| Package | Affected versions | Patched versions |
|---|---|---|
| github.com/mattermost/mattermost-server | ≥ 10.11.0, < 10.11.17≥ 10.11.0+incompatible, < 10.11.17+incompatible≥ 11.5.0, < 11.5.5≥ 11.5.0+incompatible, < 11.5.5+incompatible≥ 11.6.0, < 11.6.1≥ 11.6.0+incompatible, < 11.6.1+incompatible | 10.11.1710.11.17+incompatible11.5.511.5.5+incompatible11.6.111.6.1+incompatible |
| github.com/mattermost/mattermost-server/v5 | all versions | |
| github.com/mattermost/mattermost-server/v6 | all versions | |
| github.com/mattermost/mattermost/server/v8 | ≥ 8.0.0-20250731163400-5b955468ea1e, < 8.0.0-20260428151657-c79c3831061a | 8.0.0-20260428151657-c79c3831061a |
| mattermost server | ≥ 10.11.0, < 10.11.17≥ 11.5.0, < 11.5.5≥ 11.6.0, < 11.6.2 | 10.11.17 |
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via direct message channels by pre-registering a user account with a predictable plugin bot username. Mattermost Advisory ID: MMSA-2026-00649
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