Detection Guidance

This vulnerability involves Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, and 11.4.x <= 11.4.3 where the create_post channel permission is not checked during post edit operations. Detection would involve identifying if your Mattermost instance is running one of these affected versions.

To detect exploitation attempts on your network or system, you can monitor API requests to the post update and patch endpoints, especially those made by authenticated users whose posting privileges have been revoked.

Specific commands are not provided in the available resources or CVE description.

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Mitigation Strategies

Immediate mitigation steps include upgrading your Mattermost installation to a version later than 11.5.1, 10.11.13, or 11.4.3 where this issue is fixed.

Additionally, review and restrict API access to the post update and patch endpoints to prevent unauthorized post modifications.

Monitor Mattermost Security Updates for official patches and advisories.

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Executive Summary

This vulnerability affects certain versions of Mattermost (11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3) where the system fails to check the create_post channel permission during post edit operations.

As a result, an authenticated attacker whose posting privileges have been revoked can still modify their existing posts by sending direct API requests to the post update and patch endpoints.

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Impact Analysis

This vulnerability allows an attacker who no longer has permission to create posts to still edit their existing posts.

This could lead to unauthorized modification of content within channels, potentially undermining trust, causing misinformation, or bypassing moderation controls.

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