CVE-2026-28759
CVE.org · Published
- Record status
- Published
- Identifier year (not publication year)
- 2026
- Source publication
- Source updated
- Imported by cveboard
- Source snapshot
- cve_2026-10-24_midnight_baseline ·
CNA source text (English)
Insufficient authorization in shared channel membership sync allows remote cluster to remove users from arbitrary channels
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate that a remote cluster has access to a channel before processing membership removal requests during shared channel membership sync, which allows a malicious remote cluster to remove any user from any channel, including private channels, via crafted membership sync messages targeting channels the remote cluster is not authorized to access. Mattermost Advisory ID: MMSA-2026-00576
Scoped product and version facts
Fix information unknown; no fixed version is derived here. Missing information does not prove that no fix exists.
Exploitation unknown; this catalogue does not assess exploitation.
Mattermost
- Vendor
- Mattermost
- Product
- Mattermost
- Platforms
- Unknown
- Default status
unaffected
| Version (version) | Status (status) | Version scheme (versionType) | Exclusive end (lessThan) | Inclusive end (lessThanOrEqual) | Status changes (at → status) |
|---|---|---|---|---|---|
| 11.5.0 | affected | semver | Unavailable | 11.5.1 | None listed |
| 10.11.0 | affected | semver | Unavailable | 10.11.13 | None listed |
| 11.4.0 | affected | semver | Unavailable | 11.4.3 | None listed |
| 11.6.0 | unaffected | Unavailable | Unavailable | Unavailable | None listed |
| 11.5.2 | unaffected | Unavailable | Unavailable | Unavailable | None listed |
| 10.11.14 | unaffected | Unavailable | Unavailable | Unavailable | None listed |
| 11.4.4 | unaffected | Unavailable | Unavailable | Unavailable | None listed |