7596 matches found
CVE-2026-9571
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...
CVE-2026-6850
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-2026-10103
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-2026-10106
Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify that the channel referenced in an action cookie matches the channel of the target post, which allows an authenticated user without access to a private channel to trigger interactive post actions on posts in th...
CVE-2026-10085
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-2026-9597 Deactivated guest accounts can authenticate via magic-link token in Mattermost REST API login endpoint
Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4 fail to verify whether a guest account is deactivated before creating a session in the magic-link token login path, which allows a deactivated guest user to obtain a fully functional session via a magic-link token issued prior to deactivation...
CVE-2026-9597
Mattermost advisory MMSA-2026-00681 documents a vulnerability in Mattermost where versions 11.7.x <= 11.7.2 and 11.6.x
CVE-2026-9597 Deactivated guest accounts can authenticate via magic-link token in Mattermost REST API login endpoint
Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4 fail to verify whether a guest account is deactivated before creating a session in the magic-link token login path, which allows a deactivated guest user to obtain a fully functional session via a magic-link token issued prior to deactivation...
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-2026-6850 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-2026-6850 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-2026-6850
Mattermost is affected (versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x
CVE-2026-10106 Unauthorized users can trigger interactive post actions in private channels via action cookie channel mismatch in Mattermost
Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify that the channel referenced in an action cookie matches the channel of the target post, which allows an authenticated user without access to a private channel to trigger interactive post actions on posts in th...
CVE-2026-10106
Mattermost vulnerable versions: 11.7.x ≤ 11.7.2, 11.6.x ≤ 11.6.4, and 10.11.x ≤ 10.11.19. The issue stems from failing to verify that the channel referenced in an action cookie matches the target post’s channel, enabling an authenticated user without access to a private channel to trigger interac...
CVE-2026-10106 Unauthorized users can trigger interactive post actions in private channels via action cookie channel mismatch in Mattermost
Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify that the channel referenced in an action cookie matches the channel of the target post, which allows an authenticated user without access to a private channel to trigger interactive post actions on posts in th...
CVE-2026-10085
Mattermost is affected in versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, and 10.11.x
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 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...