CVE-2026-4274
5.4
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Summary
Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to restrict team-level access when processing membership sync from a remote cluster, which allows a malicious remote cluster to grant a user access to an entire private team instead of only the shared channel via sending crafted membership sync messages that trigger team membership assignment. Mattermost Advisory ID: MMSA-2026-00574
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Mattermost | Mattermost | 11.2.0 <= 11.2.2 | affected |
| Mattermost | Mattermost | 10.11.0 <= 10.11.10 | affected |
| Mattermost | Mattermost | 11.4.0 <= 11.4.0 | affected |
| Mattermost | Mattermost | 11.3.0 <= 11.3.1 | affected |
| Mattermost | Mattermost | 11.5.0 | unaffected |
| Mattermost | Mattermost | 11.2.3 | unaffected |
| Mattermost | Mattermost | 10.11.11 | unaffected |
| Mattermost | Mattermost | 11.4.1 | unaffected |
| Mattermost | Mattermost | 11.3.2 | unaffected |
Weaknesses
- CWE-863: CWE-863: Incorrect Authorization
ADP Enrichment
CISA ADP Vulnrichment
- SSVC:
- Exploitation: none
- Automatable: no
- Technical Impact: partial
References
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