CVE-2026-28759
6 advisories.
Go/github.com/mattermost/mattermost/server/v8 CVE-2026-28759: medium 4.3, EPSS 0.25%
Mattermost does not verify remote cluster channel access when processing shared channel membership removals
Action: Upgrade github.com/mattermost/mattermost/server/v8 to 8.0.0-20260216150504-8738f8c4b3d4 or later.
go get github.com/mattermost/mattermost/server/v8@v11.5.2go get github.com/mattermost/mattermost/server/v8@v10.11.14go get github.com/mattermost/mattermost/server/v8@v11.4.4go get github.com/mattermost/mattermost/server/v8@v8.0.0-20260216150504-8738f8c4b3d4Affected
| introduced | fixed | last affected |
|---|---|---|
| 11.5.0 | 11.5.2 | - |
| 10.11.0 | 10.11.14 | - |
| 11.4.0 | 11.4.4 | - |
| 0 | 8.0.0-20260216150504-8738f8c4b3d4 | - |
Fixed versions
| 11.5.2 | 10.11.14 | 11.4.4 | 8.0.0-20260216150504-8738f8c4b3d4 |
Sources
- osv: GHSA-8h9w-w78c-vvr3
- https://nvd.nist.gov/vuln/detail/CVE-2026-28759
- https://github.com/mattermost/mattermost/commit/8738f8c4b3d42b2b687a6231e72f313357a2e891
- https://github.com/mattermost/mattermost
- https://mattermost.com/security-updates
CVE-2026-28759 · published · modified · JSON
Go/github.com/mattermost/mattermost-server CVE-2026-28759: medium 4.3, EPSS 0.25%
Mattermost does not verify remote cluster channel access when processing shared channel membership removals
Action: Upgrade github.com/mattermost/mattermost-server to 5.3.2-0.20260216150504-8738f8c4b3d4 or later.
go get github.com/mattermost/mattermost-server@v5.3.2-0.20260216150504-8738f8c4b3d4Affected
| introduced | fixed | last affected |
|---|---|---|
| 0 | 5.3.2-0.20260216150504-8738f8c4b3d4 | - |
Fixed versions
| 5.3.2-0.20260216150504-8738f8c4b3d4 |
Sources
- osv: GHSA-8h9w-w78c-vvr3#Go/github.com/mattermost/mattermost-server
- https://nvd.nist.gov/vuln/detail/CVE-2026-28759
- https://github.com/mattermost/mattermost/commit/8738f8c4b3d42b2b687a6231e72f313357a2e891
- https://github.com/mattermost/mattermost
- https://mattermost.com/security-updates
CVE-2026-28759 · published · modified · JSON
Go/github.com/mattermost/mattermost-server CVE-2026-28759: unknown, EPSS 0.25%
Mattermost does not verify remote cluster channel access when processing shared channel membership removals in github.com/mattermost/mattermost-server
Action: Upgrade github.com/mattermost/mattermost-server to 10.11.14+incompatible or later.
go get github.com/mattermost/mattermost-server@v10.11.14+incompatiblego get github.com/mattermost/mattermost-server@v11.4.4+incompatiblego get github.com/mattermost/mattermost-server@v11.5.2+incompatibleAffected
| introduced | fixed | last affected |
|---|---|---|
| 10.11.0+incompatible | 10.11.14+incompatible | - |
| 11.4.0+incompatible | 11.4.4+incompatible | - |
| 11.5.0+incompatible | 11.5.2+incompatible | - |
Fixed versions
| 10.11.14+incompatible | 11.4.4+incompatible | 11.5.2+incompatible |
Sources
- osv: GO-2026-5256
- https://github.com/advisories/GHSA-8h9w-w78c-vvr3
- https://nvd.nist.gov/vuln/detail/CVE-2026-28759
- https://github.com/mattermost/mattermost/commit/8738f8c4b3d42b2b687a6231e72f313357a2e891
- https://mattermost.com/security-updates
CVE-2026-28759 · published · modified · JSON
Go/github.com/mattermost/mattermost-server/v5 CVE-2026-28759: unknown, EPSS 0.25%
Mattermost does not verify remote cluster channel access when processing shared channel membership removals in github.com/mattermost/mattermost-server
Action: No fix published. Pin and monitor.
Affected
| introduced | fixed | last affected |
|---|---|---|
| 0 | - | - |
Fixed versions
No fixed version in the source.
Sources
- osv: GO-2026-5256#Go/github.com/mattermost/mattermost-server/v5
- https://github.com/advisories/GHSA-8h9w-w78c-vvr3
- https://nvd.nist.gov/vuln/detail/CVE-2026-28759
- https://github.com/mattermost/mattermost/commit/8738f8c4b3d42b2b687a6231e72f313357a2e891
- https://mattermost.com/security-updates
CVE-2026-28759 · published · modified · JSON
Go/github.com/mattermost/mattermost-server/v6 CVE-2026-28759: unknown, EPSS 0.25%
Mattermost does not verify remote cluster channel access when processing shared channel membership removals in github.com/mattermost/mattermost-server
Action: No fix published. Pin and monitor.
Affected
| introduced | fixed | last affected |
|---|---|---|
| 0 | - | - |
Fixed versions
No fixed version in the source.
Sources
- osv: GO-2026-5256#Go/github.com/mattermost/mattermost-server/v6
- https://github.com/advisories/GHSA-8h9w-w78c-vvr3
- https://nvd.nist.gov/vuln/detail/CVE-2026-28759
- https://github.com/mattermost/mattermost/commit/8738f8c4b3d42b2b687a6231e72f313357a2e891
- https://mattermost.com/security-updates
CVE-2026-28759 · published · modified · JSON
Go/github.com/mattermost/mattermost/server/v8 CVE-2026-28759: unknown, EPSS 0.25%
Mattermost does not verify remote cluster channel access when processing shared channel membership removals in github.com/mattermost/mattermost-server
Action: Upgrade github.com/mattermost/mattermost/server/v8 to 8.0.0-20260216150504-8738f8c4b3d4 or later.
go get github.com/mattermost/mattermost/server/v8@v8.0.0-20260216150504-8738f8c4b3d4Affected
| introduced | fixed | last affected |
|---|---|---|
| 0 | 8.0.0-20260216150504-8738f8c4b3d4 | - |
Fixed versions
| 8.0.0-20260216150504-8738f8c4b3d4 |
Sources
- osv: GO-2026-5256#Go/github.com/mattermost/mattermost/server/v8
- https://github.com/advisories/GHSA-8h9w-w78c-vvr3
- https://nvd.nist.gov/vuln/detail/CVE-2026-28759
- https://github.com/mattermost/mattermost/commit/8738f8c4b3d42b2b687a6231e72f313357a2e891
- https://mattermost.com/security-updates
CVE-2026-28759 · published · modified · JSON