Low severity · published Mar 16, 2026
CVE-2026-26230
Team Admin Privilege Escalation to Demote Members to Guest
3.8
CVSS
0.2%
EPSS
No
On KEV
Description
Mattermost versions 10.11.x <= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 6% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
Mattermost · Mattermost
10.11.0 through 10.11.10 · source: vendor
MS
Mattermost Server · Mattermost
10.11.0 before 10.11.11 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-26230
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-26230
Vendor Advisory
https://mattermost.com/security-updates
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