Mattermost 10-11.x Auth Bypass via Action Cookie Channel Mismatch
CVE-2026-10106 Published on July 13, 2026
Unauthorized users can trigger interactive post actions in private channels via action cookie channel mismatch in Mattermost
Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to verify that the channel referenced in an action cookie matches the channel of the target post, which allows an authenticated user without access to a private channel to trigger interactive post actions on posts in that channel via a cookie obtained from any accessible channel.. Mattermost Advisory ID: MMSA-2026-00690
Vulnerability Analysis
CVE-2026-10106 is exploitable 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, a high impact on integrity, and no impact on availability.
Weakness Type
What is an AuthZ Vulnerability?
The software performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.
CVE-2026-10106 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2026-10106
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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.