CVE-2026-28759
4.3
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Summary
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
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Mattermost | Mattermost | 11.5.0 <= 11.5.1 | affected |
| Mattermost | Mattermost | 10.11.0 <= 10.11.13 | affected |
| Mattermost | Mattermost | 11.4.0 <= 11.4.3 | affected |
| Mattermost | Mattermost | 11.6.0 | unaffected |
| Mattermost | Mattermost | 11.5.2 | unaffected |
| Mattermost | Mattermost | 10.11.14 | unaffected |
| Mattermost | Mattermost | 11.4.4 | unaffected |
Weaknesses
- CWE-863: CWE-863: Incorrect Authorization
ADP Enrichment
CISA ADP Vulnrichment
- SSVC:
- Exploitation: none
- Automatable: no
- Technical Impact: partial
References
Feedback
Was this page helpful?
Glad to hear it! Please tell us how we can improve.
Sorry to hear that. Please tell us how we can improve.