Medium severity · published Mar 25, 2026
CVE-2026-27659
CSRF vulnerability in UpdateAccessControlPolicyActiveStatus endpoint
4.6
CVSS
0.1%
EPSS
No
On KEV
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 properly validate CSRF tokens in the /api/v4/access_control_policies/{policy_id}/activate endpoint, which allows an attacker to trick an admin into changing access control policy active status via a crafted request.. Mattermost Advisory ID: MMSA-2026-00578
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 2% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
Mattermost · Mattermost
11.2.0 through 11.2.2; 10.11.0 through 10.11.10; 11.4.0 through 11.4.0; 11.3.0 through 11.3.1 · source: vendor
MS
Mattermost Server · Mattermost
10.11.0 before 10.11.11; 11.2.0 before 11.2.3; 11.3.0 before 11.3.2; 11.4.0 before 11.4.1 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27659
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-27659
Vendor Advisory
https://mattermost.com/security-updates
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