Mattermost up to 11.7.9/11.8.5/11.9.1/11.10.0 DM/GM Check privileges management

Summaryinfo

A vulnerability labeled as critical has been found in Mattermost up to 11.7.9/11.8.5/11.9.1/11.10.0. This issue affects some unknown processing of the component DM/GM Check. Such manipulation leads to privileges management. This vulnerability is uniquely identified as CVE-2026-18795. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Mattermost up to 11.7.9/11.8.5/11.9.1/11.10.0. It has been rated as critical. Affected by this issue is an unknown part of the component DM/GM Check. The manipulation with an unknown input leads to a privileges management vulnerability. Using CWE to declare the problem leads to CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to enforce DM/GM check on server side which allows an authenticated user to quarantine a post belonging to DM or GM via direct API call.. Mattermost Advisory ID: MMSA-2026-00756

The advisory is shared for download at mattermost.com. This vulnerability is handled as CVE-2026-18795 since 08/04/2026. The exploitation is known to be easy. The attack may be launched remotely. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1068.

Upgrading to version 11.7.10, 11.8.6, 11.9.2, 11.10.1 or 11.11.0 eliminates this vulnerability.

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Productinfo

Type

• Groupware Software

Name

• Mattermost

Version

• 11.0
• 11.1
• 11.2
• 11.3
• 11.4
• 11.5
• 11.6
• 11.7
• 11.7.0
• 11.7.1
• 11.7.2
• 11.7.3
• 11.7.4
• 11.7.5
• 11.7.6
• 11.7.7
• 11.7.8
• 11.7.9
• 11.8
• 11.8.0
• 11.8.1
• 11.8.2
• 11.8.3
• 11.8.4
• 11.8.5
• 11.9
• 11.9.0
• 11.9.1
• 11.10.0

License

• open-source

CPE 2.3info

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CPE 2.2info

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Entryinfo

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