CVE-2026-4274 Insufficient authorization in shared channel membership sync grants team-level access instead of channel-level access

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 restrict team-level access when processing membership sync from a remote cluster, which allows a malicious remote cluster to grant a user access to an entire private team instead of only the shared...

CVE-2026-4274

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 restrict team-level access when processing membership sync from a remote cluster, which allows a malicious remote cluster to grant a user access to an entire private team instead of only the shared...

CVE-2026-4274 Insufficient authorization in shared channel membership sync grants team-level access instead of channel-level access

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 restrict team-level access when processing membership sync from a remote cluster, which allows a malicious remote cluster to grant a user access to an entire private team instead of only the shared...

PT-2026-28424

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.x through 10.11.10 Mattermost versions 11.2.x through 11.2.2 Mattermost versions 11.3.x through 11.3.1 Mattermost versions 11.4.x through 11.4.0 Description The application fails to enforce view restrictions when...

PT-2026-28425

Name of the Vulnerable Software and Affected Versions Mattermost Plugins versions 10.11.11.0 through 11.4 Description The software does not properly check the size of incoming requests, potentially allowing an authenticated attacker to disrupt service through the webhook endpoint. The issue affec...

PT-2026-28420

Name of the Vulnerable Software and Affected Versions Mattermost Plugins versions 10.11.11.0 and 11.4 Description Mattermost plugins do not properly validate timestamps in webhook requests. This allows an attacker to repeatedly send webhook requests, potentially corrupting the state of Zoom...

PT-2026-28419

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.x through 10.11.10 Mattermost versions 11.2.x through 11.2.2 Mattermost versions 11.3.x through 11.3.1 Mattermost versions 11.4.x through 11.4.0 Description The software does not properly sanitize user-controlled post...

PT-2026-28422

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.x through 10.11.11 Mattermost versions 11.2.x through 11.2.3 Mattermost versions 11.3.x through 11.3.1 Mattermost versions 11.4.x through 11.4.0 Description The software fails to properly set permissions on downloaded...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. There is a security vulnerability in Mattermost, which stems from an unvalidated target path for advanced log files. This vulnerability could allow system administrators to read arbitrary host files...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. There is a security vulnerability in Mattermost, which stems from the lack of permission settings for downloaded batch export files, potentially allowing other local users to read their contents. The...

PT-2026-28423

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.x through 10.11.11 Mattermost versions 11.2.x through 11.2.3 Mattermost versions 11.3.x through 11.3.1 Mattermost versions 11.4.x through 11.4.0 Description The software does not properly validate the size of...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. Vulnerabilities exist in Mattermost versions 11.2.2 and earlier of the 11.2.x series, as well as versions 10.11.10 and earlier of the 10.11.x series, 11.4.0 and earlier of the 11.4.x series, and 11.3...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. There is a security vulnerability in Mattermost, which stems from the lack of verification of the size of extracted files during decompression. This vulnerability could allow authenticated users to b...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. There is a security vulnerability in Mattermost; this vulnerability stems from the lack of view limitations when retrieving group member IDs. This could allow authenticated visitors to enumerate user...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. There is a security vulnerability in Mattermost, which stems from the failure to clean up post content controlled by users. This vulnerability could allow attackers to manipulate administrator...

Mattermost Plugins 安全漏洞

Mattermost Plugins is a plugin provided by the American company Mattermost, offering powerful feature extensions and tight integration with servers and web/dashboard applications. There are security vulnerabilities in versions prior to 11.4, 11.0.4, 11.1.3, 11.3.2, and 10.11.11.0. These...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. Versions of Mattermost 11.4, 10.11.11.0, and earlier versions contain security vulnerabilities. These vulnerabilities stem from unvalidated Webhook request timestamps, which could allow unauthorized...

PT-2026-28421

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.x through 10.11.11 Mattermost versions 11.2.x through 11.2.3 Mattermost versions 11.3.x through 11.3.1 Mattermost versions 11.4.x through 11.4.0 Description The software does not properly validate file target paths fo...

PT-2026-28642

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.0 through 10.11.10 Mattermost versions 11.2.0 through 11.2.2 Mattermost versions 11.3.0 through 11.3.1 Mattermost versions 11.4.0 Description The software does not properly restrict team-level access when processing...

Cross-site Request Forgery (CSRF)

Overview github.com/mattermost/mattermost/server/channels/app is a private-cloud Slack alternative Affected versions of this package are vulnerable to Cross-site Request Forgery CSRF via the UpdateAccessControlPolicyActiveStatus endpoint. An attacker can change the active status of access control...