CVE-2026-10819 Mattermost Server Denial of Service via Animated GIF Emoji Upload

Mattermost versions 11.6.x = 11.6.5, 10.11.x = 10.11.20, 11.8.x = 11.8.1, 11.7.x = 11.7.4 fail to limit the number of frames and enforce the file size cap on animated GIF uploads, which allows an authenticated attacker to cause a denial of service via a crafted animated GIF uploaded as a custom...

CVE-2026-10819

The CVE CVE-2026-10819 affects Mattermost server versions 11.6.x <= 11.6.5, 10.11.x <= 10.11.20, 11.8.x <= 11.8.1, and 11.7.x

CVE-2026-10600

Mattermost Server vulnerability CVE-2026-10600 affects multiple release lines (Mattermost 11.8.x up to 11.8.0, 11.7.x up to 11.7.3, 11.6.x up to 11.6.5, 10.11.x up to 10.11.20). An authenticated user with file-upload permission can trigger unbounded server-side document content extraction, failin...

CVE-2026-10600 Denial of service via unbounded document content extraction in Mattermost Server

Mattermost versions 11.8.x = 11.8.0, 11.7.x = 11.7.3, 11.6.x = 11.6.5, 10.11.x = 10.11.20 fail to bound the time and resource consumption of server-side document content extraction which allows an authenticated user with file-upload permission to degrade file uploads for all users on the server v...

Mattermost Server 10.11.x < 10.11.20 / 11.6.x < 11.6.5 / 11.7.x < 11.7.2 Incorrect Authorization (MMSA-2026-00653)

The version of Mattermost Server installed on the remote host is affected by a vulnerability as referenced in the MMSA-2026-00653 advisory. - Mattermost versions 11.7.x = 11.7.1, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to restrict metric configuration changes to the playbook being saved, which...

Authentication Bypass by Primary Weakness

Overview Affected versions of this package are vulnerable to Authentication Bypass by Primary Weakness in the OAuth refresh token grant process. An attacker can maintain unauthorized access by using a valid refresh token associated with a deactivated account. Remediation Upgrade...

GO-2026-5818 Mattermost doesn't sanitize team member data when returned via API to users without elevated permissions in github.com/mattermost/mattermost-server

Mattermost doesn't sanitize team member data when returned via API to users without elevated permissions in github.com/mattermost/mattermost-server...

GO-2026-5835 Mattermost doesn't validate the TIFF IFD offset in the image header before allocating memory in github.com/mattermost/mattermost-server

Mattermost doesn't validate the TIFF IFD offset in the image header before allocating memory in github.com/mattermost/mattermost-server...

GO-2026-5838 Mattermost doesn't properly validate msgpack-encoded WebSocket frames before memory allocation in github.com/mattermost/mattermost-server

Mattermost doesn't properly validate msgpack-encoded WebSocket frames before memory allocation in github.com/mattermost/mattermost-server...

GO-2026-5817 Mattermost doesn't validate file ownership and access control in github.com/mattermost/mattermost-server

Mattermost doesn't validate file ownership and access control in github.com/mattermost/mattermost-server...

GO-2026-5769 Mattermost doesn't validate the X-Requested-With header on the burn-on-read reveal endpoint in github.com/mattermost/mattermost-server

Mattermost doesn't validate the X-Requested-With header on the burn-on-read reveal endpoint in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing...

GO-2026-5671 Mattermost doesn't validate the Host header when constructing response URLs for custom slash command in github.com/mattermost/mattermost-server

Mattermost doesn't validate the Host header when constructing response URLs for custom slash command in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is...

GO-2026-5651 Mattermost doesn't check the create_post channel permission during post edit operations in github.com/mattermost/mattermost-server

Mattermost doesn't check the createpost channel permission during post edit operations in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing...

GO-2026-5726 Mattermost doesn't enforce slash command trigger-word uniqueness during command updates in github.com/mattermost/mattermost-server

Mattermost doesn't enforce slash command trigger-word uniqueness during command updates in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing...

GO-2026-5727 Mattermost doesn't prevent disclosure of created user password in github.com/mattermost/mattermost-server

Mattermost doesn't prevent disclosure of created user password in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is causing false-positive reports from...

GO-2026-5663 Mattermost doesn't validate decompressed archive entry sizes during file extraction in github.com/mattermost/mattermost-server

Mattermost doesn't validate decompressed archive entry sizes during file extraction in github.com/mattermost/mattermost-server...

GO-2026-5629 Mattermost doesn't properly validate CSRF tokens in github.com/mattermost/mattermost-server

Mattermost doesn't properly validate CSRF tokens in github.com/mattermost/mattermost-server...

GO-2026-5522 Mattermost doesn't validate whether users were correctly owned by the correct Connected Workspace in github.com/mattermost/mattermost-server

Mattermost doesn't validate whether users were correctly owned by the correct Connected Workspace in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If this is...

GO-2026-5484 Mattermost doesn't escape some variables that could contain malicious content during error page composition in github.com/mattermost/mattermost-server

Mattermost doesn't escape some variables that could contain malicious content during error page composition in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If...

GO-2026-5432 Mattermost doesn't validate that the RefreshedToken differs from the original invite token during remote cluster invite confirmation in github.com/mattermost/mattermost-server

Mattermost doesn't validate that the RefreshedToken differs from the original invite token during remote cluster invite confirmation in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standar...