CVE-2026-9162
Published:June 22, 2026
Updated:August 04, 2026
Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to invalidate cached authentication state for active WebSocket connections during global session revocation, which allows a user with an existing WebSocket connection to remain authenticated and continue receiving real-time events until the cached session expires or the client reconnects.. Mattermost Advisory ID: MMSA-2026-00664
Affected Packages
github.com/mattermost/mattermost (GO):
Affected version(s) >=v11.5.1 <v11.5.6+incompatibleFix Suggestion:
Update to version v11.5.6+incompatiblegithub.com/mattermost/mattermost (GO):
Affected version(s) >=v10.11.0+incompatible <v10.11.18+incompatibleFix Suggestion:
Update to version v10.11.18+incompatiblegithub.com/mattermost/mattermost (GO):
Affected version(s) >=v11.6.1-rc1 <v11.6.3+incompatibleFix Suggestion:
Update to version v11.6.3+incompatibleRelated Resources (3)
Do you need more information?
Contact UsCVSS v4
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
NONE
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
4.3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Weakness Type (CWE)
Insufficient Session Expiration
EPSS
Base Score:
0.33