CVE-2026-6046
Fixed in a distro release EPSS <1%CVSS 5.3
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
Products: Mattermost
Fixed upstream
| Ecosystem | Package | Fixed in |
|---|---|---|
| Go | github.com/mattermost/mattermost-server | 11.6.1 |
| Go | github.com/mattermost/mattermost-server | 11.5.5 |
| Go | github.com/mattermost/mattermost-server | 10.11.17 |
| Go | github.com/mattermost/mattermost-server | 10.11.17+incompatible |
| Go | github.com/mattermost/mattermost-server | 11.5.5+incompatible |
| Go | github.com/mattermost/mattermost-server | 11.6.1+incompatible |
| Go | github.com/mattermost/mattermost-server/v5 | no fix |
| Go | github.com/mattermost/mattermost-server/v6 | no fix |
| Go | github.com/mattermost/mattermost/server/v8 | 8.0.0-20260428151657-c79c3831061a |
Distro releases
| Release | Package | Fixed in |
|---|---|---|
| SUSE Linux Enterprise Server 16.0 | govulncheck-vulndb | 0.0.20260827T195228-160000.1.1 |
| SUSE Linux Enterprise Server for SAP applications 16.0 | govulncheck-vulndb | 0.0.20260827T195228-160000.1.1 |
| openSUSE Leap 16.0 | govulncheck-vulndb | 0.0.20260827T195228-160000.1.1 |