CVE-2026-6062
Published:June 22, 2026
Updated:September 22, 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 validate channel ownership of an existing subscription before applying edits which allows an authenticated attacker to hijack subscriptions from channels they have no access to via a crafted PUT request to the subscription edit endpoint.. Mattermost Advisory ID: MMSA-2026-00650
Affected Packages
github.com/mattermost/mattermost-server (GO):
Affected version(s) >=v11.5.0 <v11.5.6Fix Suggestion:
Update to version v11.5.6github.com/mattermost/mattermost (GO):
Affected version(s) >=v11.6.1-rc1 <v11.6.3+incompatibleFix Suggestion:
Update to version v11.6.3+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) >=v11.5.1 <v11.5.6+incompatibleFix Suggestion:
Update to version v11.5.6+incompatiblegithub.com/mattermost/mattermost-server (GO):
Affected version(s) >=v11.7.0 <v11.7.1Fix Suggestion:
Update to version v11.7.1github.com/mattermost/mattermost-server (GO):
Affected version(s) >=v11.6.0 <v11.6.3Fix Suggestion:
Update to version v11.6.3github.com/mattermost/mattermost-server (GO):
Affected version(s) >=v10.11.0 <v10.11.18Fix Suggestion:
Update to version v10.11.18Related Resources (4)
Do you need more information?
Contact UsCVSS v4
Base Score:
6.1
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
LOW
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.4
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
LOW
Availability
LOW
Weakness Type (CWE)
Authorization Bypass Through User-Controlled Key
EPSS
Base Score:
0.24