GHSA-2v3w-6g35-5f9v
Mattermost fails to properly validate User-Agent header tokens
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| Go | github.com/mattermost/mattermost/server/v8 | < 8.0.0-20260129181235-1346cf529aef | 8.0.0-20260129181235-1346cf529aef |
| Go | github.com/mattermost/mattermost-server | < 5.3.2-0.20260129181235-1346cf529aef | 5.3.2-0.20260129181235-1346cf529aef |
| Go | github.com/mattermost/mattermost-server | >= 10.11.0-rc1, < 10.11.11 | 10.11.11 |
| Go | github.com/mattermost/mattermost-server | >= 11.2.0-rc1, < 11.2.3 | 11.2.3 |
| Go | github.com/mattermost/mattermost-server | >= 11.3.0-rc1, < 11.3.1 | 11.3.1 |
Details
As written in the advisory (Markdown source, shown as plain text).
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly validate User-Agent header tokens which allows an authenticated attacker to cause a request panic via a specially crafted User-Agent header. Mattermost Advisory ID: MMSA-2026-00586
References
External links from the advisory. They lead to third-party sites.