SUSE CVE-2026-4858

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action...

SUSE CVE-2026-6340

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to validate 7zip archive structure before processing which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted 7zip file with excessive folder...

SUSE CVE-2026-6343

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to check public/private permissions which allows members without these permissions to access public playbooks via /get.. Mattermost Advisory ID: MMSA-2026-00591...

SUSE CVE-2026-28735

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to validate the OAuth token scope on the callback which allows an authenticated Mattermost user to gain access to private repositories via modifying the scope parameter in the GitHub authorization URL...

CVE-2026-7521

Mattermost CVE-2026-7521 affects versions 11.8.x up to 11.8.0, 11.7.x up to 11.7.3, 11.6.x up to 11.6.5, and 10.11.x up to 10.11.20. The issue arises from a failure to verify the file deletion path in the remove file endpoint for SAML admin writes, enabling deletion of arbitrary files outside the...

CVE-2026-7521 SAML certificate deletion allows path traversal to delete arbitrary files outside the config directory

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 verify file deletion path which allows an admin with SAML system-console write permissions to delete arbitrary files outside the config directory from the server via the remove file endpoint...

PT-2026-65500

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 verify file deletion path which allows an admin with SAML system-console write permissions to delete arbitrary files outside the config directory from the server via the remove file endpoint...

CVE-2026-6541 Unscoped updates to other playbooks' metric configuration

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 allows an authenticated user with team access to alter another user’s playbook metric settings via a crafted import or update request with a...

EUVD-2026-43341

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 allows an authenticated user with team access to alter another user’s playbook metric settings via a crafted import or update request with a...

CVE-2026-6541 Unscoped updates to other playbooks' metric configuration

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 allows an authenticated user with team access to alter another user’s playbook metric settings via a crafted import or update request with a...

EUVD-2026-43340

Mattermost versions 11.7.x = 11.7.2, 10.11.x = 10.11.19 fail to sanitize team objects returned by the scheme teams endpoint, which allows a user with the User Manager role to obtain invite links for private teams and use them to join or share access to those teams via the scheme teams API...

CVE-2026-9824 Remote cluster metadata enumeration via /share-channel autocomplete

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to check the managesharedchannels permission in the /share-channel autocomplete handler, which allows an authenticated user without that permission to enumerate configured remote cluster connection metadata via slash...

CVE-2026-9824 Remote cluster metadata enumeration via /share-channel autocomplete

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to check the managesharedchannels permission in the /share-channel autocomplete handler, which allows an authenticated user without that permission to enumerate configured remote cluster connection metadata via slash...

EUVD-2026-43307

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify post ownership in the shared channel inbound sync handler, which allows an authenticated remote cluster to modify or delete posts authored by local users or other remotes via crafted sync messages referencing...

CVE-2026-6850 Crafted message attachment causes client-side denial of service via markdown parser regex backtracking in Mattermost

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to validate the length and content of message attachment field values, which allows an authenticated attacker to cause a denial of service for all users in a channel via a post containing a specially crafted payload tha...

CVE-2026-10085 Ordinary group/direct message member can enable group_constrained and remove all channel participants

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to restrict the groupconstrained channel flag to public and private channels that support group synchronization, which allows an ordinary group or direct message member to remove all participants from the conversation v...

CVE-2026-10085 Ordinary group/direct message member can enable group_constrained and remove all channel participants

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to restrict the groupconstrained channel flag to public and private channels that support group synchronization, which allows an ordinary group or direct message member to remove all participants from the conversation v...

CVE-2026-9708

Mattermost vulnerable versions (11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x

CVE-2026-9708 Incoming webhook user attribution via unvalidated webhook owner

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to validate that an assigned incoming webhook user has access to the target team or channel, which allows a requester with webhook management permissions to create posts or direct messages attributed to another user via...

CVE-2026-9571 Deactivated user accounts can continue to obtain valid OAuth access tokens via refresh token grant in Mattermost

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to invalidate OAuth refresh tokens upon user account deactivation, which allows a deactivated user or an attacker in possession of a valid refresh token to obtain new functional access tokens via the OAuth refresh token...