VDB
CVE-2026-4274
CVE-2026-4274
PUBLISHED
CVSS 5.400000095367432 MEDIUM
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
EPSS 0.04% · 12.3th percentile
Risk Scores
CVSS 3.1
5.400000095367432
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
EPSS Score
0.04%
12.3th percentile
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost | 10.11.11, 11.3.0, 11.5.0 |
| mattermost | mattermost_server | 11.2.0, 11.3.0, 11.4.0 |
| github.com | mattermost/mattermost/server/v8 | 10.11.0-rc1, 11.4.0-rc1, 11.3.0-rc1 |
Exploit Intelligence
- CIRCL seen: CVE-2026-4274 (circl-sighting)
- CIRCL seen: CVE-2026-4265 (circl-sighting)
- CIRCL seen: CVE-2026-4265 (circl-sighting)
- MMSA-2026-00574 (circl)
Timeline
- Mar 17, 2026 CVE Published
- Mar 17, 2026 PoC Published
- Mar 17, 2026 PoC Published
- Mar 27, 2026 EPSS Score
- Mar 27, 2026 Coalition ESS Score
- Mar 27, 2026 Security Advisory
- Mar 31, 2026 CVE Updated
- Apr 16, 2026 PoC Published
- May 18, 2026 EPSS Score
- May 19, 2026 EPSS Score
- May 20, 2026 EPSS Score
- May 21, 2026 EPSS Score
References
- MMSA-2026-00574 vendor-advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-4274 advisory
- https://mattermost.com/security-updates/ advisory
- https://github.com/mattermost/mattermost package