Go/github.com/mattermost/mattermost/server/v8 CVE-2026-21386: medium 4.3, EPSS 0.19%

Mattermost fails to use consistent error responses when handling the /mute command in github.com/mattermost/mattermost-server

Action: Upgrade github.com/mattermost/mattermost/server/v8 to 8.0.0-20260130144323-5bb5261c72fa or later.

go get github.com/mattermost/mattermost/server/v8@v8.0.0-20260130144323-5bb5261c72fa

Affected

Fixed versions

Sources

• osv: GO-2026-4744#Go/github.com/mattermost/mattermost/server/v8
• nvd: CVE-2026-21386
• https://github.com/advisories/GHSA-5mr9-crcg-8wh2
• https://github.com/mattermost/mattermost/commit/5bb5261c72faa476558a694c23581d24b734da41
• https://mattermost.com/security-updates

CVE-2026-21386 · published 2026-03-23T18:14:47Z · modified 2026-03-23T18:45:19.760351Z · JSON