Mattermost 11.7.2-10.11.19 Group Sync Channel Flag Bypass (Patch API)
CVE-2026-10085 Published on July 13, 2026
Ordinary group/direct message member can enable group_constrained and remove all channel participants
Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to restrict the group_constrained channel flag to public and private channels that support group synchronization, which allows an ordinary group or direct message member to remove all participants from the conversation via the channel patch API.. Mattermost Advisory ID: MMSA-2026-00688
Vulnerability Analysis
CVE-2026-10085 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, with no impact on integrity and availability.
Weakness Type
What is an AuthZ Vulnerability?
The software does not perform an authorization check when an actor attempts to access a resource or perform an action.
CVE-2026-10085 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2026-10085
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Affected Versions
Mattermost:- Version 11.7.0, <= 11.7.2 is affected.
- Version 11.6.0, <= 11.6.4 is affected.
- Version 10.11.0, <= 10.11.19 is affected.
- Version 11.8.0 is unaffected.
- Version 11.7.3 is unaffected.
- Version 11.6.5 is unaffected.
- Version 10.11.20 is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.