GO-2026-4521
NoneCVSS
—
EPSS
—
Published
Feb 23, 2026
CISA due date
—
The record
Mattermost fails to properly validate team membership when processing channel mentions in github.com/mattermost/mattermost-server
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | 0 | No fix |
| Go | github.com/mattermost/mattermost-server | 10.11.0+incompatible | No fix |
| Go | github.com/mattermost/mattermost-server | 11.1.0+incompatible | No fix |
| Go | github.com/mattermost/mattermost-server | 11.2.0+incompatible | No fix |
| Go | github.com/mattermost/mattermost-server/v5 | 0 | No fix |
| Go | github.com/mattermost/mattermost-server/v6 | 0 | No fix |
| Go | github.com/mattermost/mattermost/server/v8 | 0 | 8.0.0-20251209134645-761e56bb11cc |
Related vulnerabilities
- CVE-2025-14350 Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to… Same vulnerability
- GO-2026-4305 Mattermost Server vulnerable to CSRF if CORS is enabled in… Also affects github.com/mattermost/mattermost-server
- GO-2025-4259 Mattermost doesn't validate user channel membership when attaching Mattermost posts as… Also affects github.com/mattermost/mattermost-server
- GO-2026-4326 Mattermost is vulnerable to DoS due to infinite re-renders on API errors in… Also affects github.com/mattermost/mattermost-server
- GO-2025-4260 Mattermost doesn't verify that post actions invoking `/share-issue-publicly` were created… Also affects github.com/mattermost/mattermost-server
- GO-2026-4325 Mattermost is vulnerable to CPU exhaustion via crafted HTTP request in… Also affects github.com/mattermost/mattermost-server
- GO-2026-4282 Mattermost Server is vulnerable to channel invisibility DoS via misformatted post in… Also affects github.com/mattermost/mattermost-server
- GO-2026-4496 Mattermost doesn't validate user permissions when creating Jira issues from Mattermost… Also affects github.com/mattermost/mattermost-server