SUSE CVE-2026-3636

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 sanitize team member data when returned via API to users without elevated permissions which allows a user without permissions to get data about team members roles via invoking various team API...

SUSE CVE-2026-3637

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...

SUSE CVE-2026-6345

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail prevent disclosure of created user password which allows a malicious attacker to impersonate a user via the use of some of those passwords.. Mattermost Advisory ID: MMSA-2026-00614...

CVE-2026-7521

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-2026-10819

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-2026-9820

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-2026-6541

CVE-2026-6541 affects Mattermost versions 11.7.x <= 11.7.1, 11.6.x <= 11.6.4, and 10.11.x

Authentication Bypass by Primary Weakness

Overview Affected versions of this package are vulnerable to Authentication Bypass by Primary Weakness in the magic-link token authentication process. An attacker can gain unauthorized access to a deactivated guest account by using a previously issued magic-link token. Remediation Upgrade...

The vulnerability of the Mattermost instant messaging application, related to deficiencies in authentication procedures, allows attackers to bypass existing security mechanisms.

The vulnerability of the Mattermost instant messaging application is related to deficiencies in authentication procedures. Exploiting this vulnerability could allow a malicious actor to bypass existing security measures remotely...

CVE-2026-6673

Mattermost versions 11.7.x = 11.7.0, 11.6.x = 11.6.2, 11.5.x = 11.5.5, 10.11.x = 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the...

CVE-2026-5139 GitLab Plugin Allows Non-Admin Users to Modify Default Instance Configuration

Mattermost versions 11.7.x slash command.. Mattermost Advisory ID: MMSA-2026-00644...

CVE-2026-6739

Mattermost versions 11.6.x = 11.6.1, 11.5.x = 11.5.4, 10.11.x = 10.11.15, 10.11.x = 10.11.16 fail to require system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions to escalate privileges by altering built-i...

EUVD-2026-36502

Mattermost versions 11.6.x = 11.6.1, 11.5.x = 11.5.4, 10.11.x = 10.11.15, 10.11.x = 10.11.16 fail to validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via direct message channels ...

PT-2026-48941

Name of the Vulnerable Software and Affected Versions Mattermost versions prior to 11.6.2 Mattermost versions prior to 11.5.5 Mattermost versions prior to 10.11.17 Description Insufficient role-management authorization occurs when setting the scheme admin flag on group syncable link and patch...

The vulnerability of the Mattermost instant messaging application, related to uncontrolled resource consumption, allows a hacker to cause a service failure.

The vulnerability of the Mattermost instant messaging application is related to an uncontrolled resource consumption due to the processing of large HTTP requests. Exploiting this vulnerability could allow a malicious actor to cause service interruptions...

CVE-2026-4915 Server panic via outgoing webhook responses

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 filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service server process termination via a crafted webhook...

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...

PT-2026-42751

Name of the Vulnerable Software and Affected Versions Mattermost version 11.6.0 Mattermost version 11.5.3 Mattermost version 11.4.4 Mattermost version 10.11.14 Description Authenticated users with file upload or posting permissions can cause a denial of service resulting in server Out of Memory O...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. Vulnerabilities exist in versions of Mattermost 11.6.0 and earlier 11.6.x series, as well as versions prior to 11.5.3 11.5.x series, 11.4.4 and earlier 11.4.x series, and 10.11.14 and earlier 10.11.x...

Incorrect Authorization

Overview github.com/mattermost/mattermost/server/channels/app is a private-cloud Slack alternative Affected versions of this package are vulnerable to Incorrect Authorization via the command update API. An attacker can impersonate existing system or custom commands by editing their own slash...