GO-2026-4521
Mattermost fails to properly validate team membership when processing channel mentions in github.com/mattermost/mattermost-server
Quick fix
GO-2026-4521 — github.com/mattermost/mattermost/server/v8: upgrade to the fixed version with the command below.
go get github.com/mattermost/mattermost/server/v8@v8.0.0-20251209134645-761e56bb11ccDetails
Mattermost fails to properly validate team membership when processing channel mentions in github.com/mattermost/mattermost-server.
NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions.
(If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.)
The additional affected modules and versions are: github.com/mattermost/mattermost-server/v5 before v5.3.2-0.20251209134645-761e56bb11cc.
Are you affected?
Enter the version of the package you're using.
Affected packages
0No fixed version published yet for github.com/mattermost/mattermost-server (go modules). Pin to a known-safe version or switch to an alternative.
10.11.0+incompatibleNo fixed version published yet for github.com/mattermost/mattermost-server (go modules). Pin to a known-safe version or switch to an alternative.
11.1.0+incompatibleNo fixed version published yet for github.com/mattermost/mattermost-server (go modules). Pin to a known-safe version or switch to an alternative.
11.2.0+incompatibleNo fixed version published yet for github.com/mattermost/mattermost-server (go modules). Pin to a known-safe version or switch to an alternative.
0No fixed version published yet for github.com/mattermost/mattermost-server/v5 (go modules). Pin to a known-safe version or switch to an alternative.
0No fixed version published yet for github.com/mattermost/mattermost-server/v6 (go modules). Pin to a known-safe version or switch to an alternative.
0Fixed in: 8.0.0-20251209134645-761e56bb11ccgo get github.com/mattermost/mattermost/server/v8@v8.0.0-20251209134645-761e56bb11cc