Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action URL. Mattermost Advisory ID: MMSA-2026-00640.
Update github.com/mattermost/mattermost-server to 11.6.1; github.com/mattermost/mattermost-server to 11.5.4; github.com/mattermost/mattermost-server to 11.4.5; github.com/mattermost/mattermost-server to 10.11.15 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanMattermost has a Path Traversal issue affects github.com/mattermost/mattermost-server (go), github.com/mattermost/mattermost-server (go), github.com/mattermost/mattermost-server (go), github.com/mattermost/mattermost-server (go). Severity is high. Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action URL. Mattermost Advisory ID: MMSA-2026-00640.
AI coding agents often install or upgrade packages automatically in go. A high vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| github.com/mattermost/mattermost-server |
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action URL. Mattermost Advisory ID: MMSA-2026-00640.
Update github.com/mattermost/mattermost-server to 11.6.1; github.com/mattermost/mattermost-server to 11.5.4; github.com/mattermost/mattermost-server to 11.4.5; github.com/mattermost/mattermost-server to 10.11.15 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanMattermost has a Path Traversal issue affects github.com/mattermost/mattermost-server (go), github.com/mattermost/mattermost-server (go), github.com/mattermost/mattermost-server (go), github.com/mattermost/mattermost-server (go). Severity is high. Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action URL. Mattermost Advisory ID: MMSA-2026-00640.
AI coding agents often install or upgrade packages automatically in go. A high vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| github.com/mattermost/mattermost-server |
| =11.6.0 |
| 11.6.1 |
| github.com/mattermost/mattermost-servergo | >=11.5.0,<11.5.4 | 11.5.4 |
|---|
| github.com/mattermost/mattermost-servergo | >=11.4.0,<11.4.5 | 11.4.5 |
|---|
| github.com/mattermost/mattermost-servergo | >=10.11.0,<10.11.15 | 10.11.15 |
|---|
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard| =11.6.0 |
| 11.6.1 |
| github.com/mattermost/mattermost-servergo | >=11.5.0,<11.5.4 | 11.5.4 |
|---|
| github.com/mattermost/mattermost-servergo | >=11.4.0,<11.4.5 | 11.4.5 |
|---|
| github.com/mattermost/mattermost-servergo | >=10.11.0,<10.11.15 | 10.11.15 |
|---|
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard