Medium severity · published Sep 14, 2026
CVE-2026-91181
Data Retention Teams Endpoint Leaks Private Team Invite ID
6.5
CVSS
0.4%
EPSS
No
On KEV
Description
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 Fail to sanitize Team objects returned by the data retention teams endpoint which allows an authenticated user holding only the read-only Data Retention Policy permission to obtain a private team's secret invite_id and email, and use it to join the team without authorization, via GET /api/v4/data_retention/policies/{policy_id}/teams.. Mattermost Advisory ID: MMSA-2026-00702
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 33% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
Mattermost · Mattermost
11.9.0 through 11.9.0; 11.8.0 through 11.8.4; 11.7.0 through 11.7.7; 10.11.0 through 10.11.22 · source: vendor
MS
Mattermost Server · Mattermost
10.11.0 before 10.11.23; 11.7.0 before 11.7.8; 11.8.0 before 11.8.5; 11.9.0 before 11.9.1 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-91181
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-91181
Vendor Advisory
https://mattermost.com/security-updates
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