medium4.3
CVE-2026-2458
Mattermost allows a removed team member to enumerate all public channels within a private team
Impact
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly validate team membership when searching channels which allows a removed team member to enumerate all public channels within a private team via the channel search API endpoint. Mattermost Advisory ID: MMSA-2025-00568
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/mattermost/mattermost/server/v8 | < 8.0.0-20260113182106-a18b80ba4c32 | 8.0.0-20260113182106-a18b80ba4c32 |
| go | github.com/mattermost/mattermost-server | < 5.3.2-0.20260113182106-a18b80ba4c32 | 5.3.2-0.20260113182106-a18b80ba4c32 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Mattermost | Mattermost Server | from 10.11.0 before 10.11.11 from 11.2.0 before 11.2.3 from 11.3.0 before 11.3.1 |