CVE-2026-4274

MEDIUM EPSS 3.8%
Published Mar 26, 20263mo ago · Modified Jun 17, 20261w ago
5.4 CVSS 3.1
Medium
Find Similar
Published Mar 26, 2026 3mo ago
Last Modified Jun 17, 2026 1w ago

Description

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

CVSS Details

Base Score
5.4
Exploitability
2.8
Impact
2.5
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Attack Vector Network
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality Low
Integrity Low
Availability None

Threat Intelligence

EPSS Exploit Probability
3.8% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-863 Incorrect Authorization Authorization

Affected Products 4

VendorProductVersionRange
mattermostmattermost_server*≥10.11.0  –  <10.11.11
mattermostmattermost_server*≥11.2.0  –  <11.2.3
mattermostmattermost_server*≥11.3.0  –  <11.3.2
mattermostmattermost_server*≥11.4.0  –  <11.4.1

References 1

  • mattermost.com https://mattermost.com/security-updates
    Vendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.