CVE-2026-3109

Mattermost Plugins in versions

CVE-2026-3115 Guest users can view group member IDs without respecting view restrictions

Mattermost versions 11.2.x = 11.2.2, 10.11.x = 10.11.10, 11.4.x = 11.4.0, 11.3.x = 11.3.1 fail to apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint...

CVE-2026-3115

Mattermost fixes for CVE-2026-3115 affect this product family: versions 11.2.x ≤ 11.2.2, 10.11.x ≤ 10.11.10, 11.4.x ≤ 11.4.0, and 11.3.x ≤ 11.3.1 fail to apply view restrictions when retrieving group member IDs. This allows authenticated guest users to enumerate user IDs outside their visibility ...

CVE-2026-3115

Mattermost versions 11.2.x = 11.2.2, 10.11.x = 10.11.10, 11.4.x = 11.4.0, 11.3.x = 11.3.1 fail to apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint...

CVE-2026-3115 Guest users can view group member IDs without respecting view restrictions

Mattermost versions 11.2.x = 11.2.2, 10.11.x = 10.11.10, 11.4.x = 11.4.0, 11.3.x = 11.3.1 fail to apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint...

CVE-2026-3115 Guest users can view group member IDs without respecting view restrictions

Mattermost versions 11.2.x = 11.2.2, 10.11.x = 10.11.10, 11.4.x = 11.4.0, 11.3.x = 11.3.1 fail to apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint...

CVE-2026-3114 Zip Bomb Denial of Service via Unrestricted Archive Decompression

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to validate decompressed archive entry sizes during file extraction which allows authenticated users with file upload permissions to cause a denial of service via crafted zip archives containing highly...

CVE-2026-3114

Mattermost CVE-2026-3114 affects versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, and 10.11.x

CVE-2026-3114

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to validate decompressed archive entry sizes during file extraction which allows authenticated users with file upload permissions to cause a denial of service via crafted zip archives containing highly...

CVE-2026-3114 Zip Bomb Denial of Service via Unrestricted Archive Decompression

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to validate decompressed archive entry sizes during file extraction which allows authenticated users with file upload permissions to cause a denial of service via crafted zip archives containing highly...

CVE-2026-3114 Zip Bomb Denial of Service via Unrestricted Archive Decompression

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to validate decompressed archive entry sizes during file extraction which allows authenticated users with file upload permissions to cause a denial of service via crafted zip archives containing highly...

CVE-2026-3116 Improper Input Validation in Zoom Plugin Webhook Handler

Mattermost Plugins versions =11.4 11.0.4 11.1.3 11.3.2 10.11.11.0 fail to validate incoming request size which allows an authenticated attacker to cause service disruption via the webhook endpoint. Mattermost Advisory ID: MMSA-2026-00589...

CVE-2026-3116

CVE-2026-3116 affects Mattermost Plugins with versions

CVE-2026-3116

Mattermost Plugins versions =11.4 11.0.4 11.1.3 11.3.2 10.11.11.0 fail to validate incoming request size which allows an authenticated attacker to cause service disruption via the webhook endpoint. Mattermost Advisory ID: MMSA-2026-00589...

CVE-2026-3116 Improper Input Validation in Zoom Plugin Webhook Handler

Mattermost Plugins versions =11.4 11.0.4 11.1.3 11.3.2 10.11.11.0 fail to validate incoming request size which allows an authenticated attacker to cause service disruption via the webhook endpoint. Mattermost Advisory ID: MMSA-2026-00589...

CVE-2026-3116 Improper Input Validation in Zoom Plugin Webhook Handler

Mattermost Plugins versions =11.4 11.0.4 11.1.3 11.3.2 10.11.11.0 fail to validate incoming request size which allows an authenticated attacker to cause service disruption via the webhook endpoint. Mattermost Advisory ID: MMSA-2026-00589...

CVE-2026-3113

CVE-2026-3113 affects Mattermost (versions listed) where bulk exports fail to enforce file permissions during download, enabling other local server users to read exported contents. Root cause: permissions are not properly set on the downloaded bulk export, allowing access beyond the intended owne...

CVE-2026-3113

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to set permissions on downloaded bulk export which allows other local users on the server to be able to read contents of the bulk export.. Mattermost Advisory ID: MMSA-2026-00593...

CVE-2026-3113 mmctl export download command doesn’t restrict permissions to created file to file owner

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to set permissions on downloaded bulk export which allows other local users on the server to be able to read contents of the bulk export.. Mattermost Advisory ID: MMSA-2026-00593...

CVE-2026-3113 mmctl export download command doesn’t restrict permissions to created file to file owner

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to set permissions on downloaded bulk export which allows other local users on the server to be able to read contents of the bulk export.. Mattermost Advisory ID: MMSA-2026-00593...