Missing Authorization

Overview github.com/mattermost/mattermost/server/channels/app is a private-cloud Slack alternative Affected versions of this package are vulnerable to Missing Authorization via the post rewrite endpoint. An attacker can gain unauthorized access to the content of threads in private channels and...

Incorrect Authorization

Overview Affected versions of this package are vulnerable to Incorrect Authorization via the API-level authorization process. An attacker can create issues or attach comments to a locked group by sending direct API requests as a member of multiple groups. Remediation Upgrade...

Mattermost doesn't verify channel membership when processing AI-assisted message rewrites

Mattermost versions 11.5.x = 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite...

GHSA-8R89-8W26-CQ32 Mattermost doesn't verify channel membership when processing AI-assisted message rewrites

Mattermost versions 11.5.x = 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite...

Mattermost doesn't check the create_post channel permission during post edit operations

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to check the createpost channel permission during post edit operations which allows an authenticated attacker with revoked posting privileges to modify their existing posts via direct API requests to the post update and...

CVE-2026-5163

Mattermost versions 11.5.x = 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite...

CVE-2026-5163

Mattermost versions 11.5.x = 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite...

CVE-2026-5163 Missing authorization check in AI message rewrite endpoint allows access to private thread content

Mattermost versions 11.5.x = 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite...

EUVD-2026-30753

Mattermost versions 11.5.x = 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite...

CVE-2026-6341 Incomplete group locking implementation

Mattermost Plugins versions =11.5 11.1.5 10.13.11 11.3.4.0 fail to have API-level checks on which groups the user can create issues or attach comments to which allows a user that is member of multiple groups to create issues to a locked group via direct API requests. Mattermost Advisory ID:...

EUVD-2026-30746

Mattermost Plugins versions =11.5 11.1.5 10.13.11 11.3.4.0 fail to have API-level checks on which groups the user can create issues or attach comments to which allows a user that is member of multiple groups to create issues to a locked group via direct API requests. Mattermost Advisory ID:...

CVE-2026-6341

Mattermost Plugins versions =11.5 11.1.5 10.13.11 11.3.4.0 fail to have API-level checks on which groups the user can create issues or attach comments to which allows a user that is member of multiple groups to create issues to a locked group via direct API requests. Mattermost Advisory ID:...

CVE-2026-6341 Incomplete group locking implementation

Mattermost Plugins versions =11.5 11.1.5 10.13.11 11.3.4.0 fail to have API-level checks on which groups the user can create issues or attach comments to which allows a user that is member of multiple groups to create issues to a locked group via direct API requests. Mattermost Advisory ID:...

CVE-2026-3637 Mattermost fails to enforce create_post permission when editing posts

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to check the createpost channel permission during post edit operations which allows an authenticated attacker with revoked posting privileges to modify their existing posts via direct API requests to the post update and...

CVE-2026-3637 Mattermost fails to enforce create_post permission when editing posts

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to check the createpost channel permission during post edit operations which allows an authenticated attacker with revoked posting privileges to modify their existing posts via direct API requests to the post update and...

Mattermost Plugins 安全漏洞

Mattermost Plugins is a plugin provided by the American company Mattermost, offering powerful feature extensions and tight integration with servers and network/desktop applications. Versions 11.5, 11.1.5, 10.13.11, and 11.3.4.0 of Mattermost Plugins contain security vulnerabilities. These...

PT-2026-41655

Name of the Vulnerable Software and Affected Versions Mattermost versions 11.5.x through 11.5.1 Description An issue exists where channel membership is not verified during the processing of AI-assisted message rewrites. This allows an authenticated attacker to read the content of threads in priva...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. Versions of Mattermost such as 11.5.1 and earlier 11.5.x series, 10.11.13 and earlier 10.11.x series, and 11.4.3 and earlier 11.4.x series have security vulnerabilities. These vulnerabilities stem fr...

PT-2026-41642

Name of the Vulnerable Software and Affected Versions Mattermost versions 11.5.0 through 11.5.1 Mattermost versions 10.11.0 through 10.11.13 Mattermost versions 11.4.0 through 11.4.3 Description An issue exists where the software fails to verify the create post channel permission during post edit...

CVE-2026-44504

Aegra is a drop-in replacement for LangSmith Deployments. Prior to 0.9.7, with multiple authenticated users on a shared instance are vulnerable to a cross-tenant IDOR. Any authenticated attacker, given another user's threadid, can execute graph runs against the user's thread, read the user's full...