GHSA-vqp5-2mrp-qqxg
Mattermost doesn't validate the Host header when constructing response URLs for custom slash command
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| Go | github.com/mattermost/mattermost/server/v8 | >= 11.5.0, < 11.5.2 | 11.5.2 |
| Go | github.com/mattermost/mattermost/server/v8 | >= 10.11.0, < 10.11.14 | 10.11.14 |
| Go | github.com/mattermost/mattermost/server/v8 | < 8.0.0-20260325160634-e738016c5920 | 8.0.0-20260325160634-e738016c5920 |
| Go | github.com/mattermost/mattermost-server | < 5.3.2-0.20260325160634-e738016c5920 | 5.3.2-0.20260325160634-e738016c5920 |
Details
As written in the advisory (Markdown source, shown as plain text).
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost Advisory ID: MMSA-2026-00582
References
External links from the advisory. They lead to third-party sites.