CVE-2026-2458

Mattermost versions 11.3.x = 11.3.0, 11.2.x = 11.2.2, 10.11.x = 10.11.10 fail to properly validate team membership when searching channels which allows a removed team member to enumerate all public channels within a private team via the channel search API endpoint.. Mattermost Advisory ID:...

Mattermost has an Incorrect Authorization issue

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...

GHSA-G7FP-CQJ5-X8HF Mattermost has an Incorrect Authorization issue

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...

Incorrect Authorization

Overview Affected versions of this package are vulnerable to Incorrect Authorization in the membership synchronization process. An attacker can gain unauthorized access to an entire private team by sending crafted membership synchronization messages from a remote cluster that trigger team...

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

Mattermost CVE-2026-4274 affects multiple release lines: 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, and 11.3.x

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-2026-28642

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...

Missing Authorization

Overview Affected versions of this package are vulnerable to Missing Authorization in the channel search API endpoint. An attacker can access information about all public channels within a private team by querying the API after being removed from the team. Remediation Upgrade...

Missing Authorization

Overview Affected versions of this package are vulnerable to Missing Authorization in the channel search API endpoint. An attacker can access information about all public channels within a private team by querying the API after being removed from the team. Remediation Upgrade...

GHSA-679F-WMRG-QF57 Mattermost allows a removed team member to enumerate all public channels within a private team

Mattermost versions 11.3.x = 11.3.0, 11.2.x = 11.2.2, 10.11.x = 10.11.10 fail to properly validate team membership when searching channels which allows a removed team member to enumerate all public channels within a private team via the channel search API endpoint. Mattermost Advisory ID:...

Mattermost allows a removed team member to enumerate all public channels within a private team

Mattermost versions 11.3.x = 11.3.0, 11.2.x = 11.2.2, 10.11.x = 10.11.10 fail to properly validate team membership when searching channels which allows a removed team member to enumerate all public channels within a private team via the channel search API endpoint. Mattermost Advisory ID:...

CVE-2026-2458

Mattermost versions 11.3.x = 11.3.0, 11.2.x = 11.2.2, 10.11.x = 10.11.10 fail to properly validate team membership when searching channels which allows a removed team member to enumerate all public channels within a private team via the channel search API endpoint.. Mattermost Advisory ID:...

PT-2026-25684

Mattermost allows a removed team member to enumerate all public channels within a private team 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 causi...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. Versions of Mattermost such as 11.3.0 and earlier 11.3.x series, 11.2.2 and earlier 11.2.x series, as well as 10.11.10 and earlier 10.11.x series, have security vulnerabilities. These vulnerabilities...

Mattermost Server exposes private team invite ID

An issue was discovered in Mattermost Server before 4.1.0, 4.0.4, and 3.10.3. It allows attackers to discover a team invite ID by requesting a JSON document...