CVE-2026-27769 Connected Workspaces: Malicious remote server can manipulate arbitrary user's status

Mattermost versions 10.11.x = 10.11.12 fail to validate whether users were correctly owned by the correct Connected Workspace which allows a malicious remote server connected using the Conntexted Workspaces feature to change the displayed status of local users via the Connected Workspaces API...

CVE-2026-27769

Mattermost versions 10.11.x = 10.11.12 fail to validate whether users were correctly owned by the correct Connected Workspace which allows a malicious remote server connected using the Conntexted Workspaces feature to change the displayed status of local users via the Connected Workspaces API...

CVE-2026-27769

Mattermost CVE-2026-27769 affects Mattermost 10.11.x up to 10.11.12 where the Connected Workspaces feature does not validate that users are correctly owned by the target Connected Workspace. This allows a malicious remote server connected via the Connected Workspaces API to change the displayed s...

PT-2026-33054

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.0 through 10.11.12 Mattermost version 11.5.0 Mattermost versions 11.4.0 through 11.4.2 Mattermost versions 11.3.0 through 11.3.2 Description Failure to enforce atomic single-use consumption of guest magic link tokens...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. Versions of Mattermost such as 10.11.12 and earlier, including 10.11.x, have security vulnerabilities. These vulnerabilities stem from unvalidated user ownership, which could allow malicious remote...

PT-2026-33036

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.x through 10.11.12 Description Improper validation of user ownership within the Connected Workspaces feature allows a malicious remote server to change the displayed status of local users via the Connected Workspaces...

Mattermost 安全漏洞

Mattermost is an open-source collaboration platform developed by the American company Mattermost. Vulnerabilities exist in Mattermost versions 10.11.12 and earlier of the 10.11.x series, as well as versions 11.5.0 and earlier of the 11.5.x series, 11.4.2 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 authentication endpoint not verifying the CSRF token. This could allow attackers to update users’ authentication methods through...

PT-2026-33037

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.0 through 10.11.12 Mattermost version 11.5.0 Mattermost versions 11.4.0 through 11.4.2 Mattermost versions 11.3.0 through 11.3.2 Description An authentication endpoint fails to validate CSRF tokens. This allows an...

Allocation of Resources Without Limits or Throttling

Overview Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the /lifecycle webhook endpoint. An attacker can exhaust system memory and disrupt service availability by sending an oversized JSON payload. Remediation Upgrade...

EUVD-2026-20880

Mattermost Plugins versions =2.3.1 fail to limit the request body size on the /lifecycle webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00610...

Mattermost MS Teams plugin doesn't limit the request body size on the /changes webhook endpoint

Mattermost Plugins versions =2.1.3.0 fail to limit the request body size on the /changes webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00611...

EUVD-2026-20882

Mattermost Plugins versions =2.1.3.0 fail to limit the request body size on the /changes webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00611...

Mattermost MS Teams plugin doesn't limit the request body size on the /lifecycle webhook endpoint

Mattermost Plugins versions =2.3.1 fail to limit the request body size on the /lifecycle webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00610...

GHSA-5RFV-H47G-XJ42 Mattermost MS Teams plugin doesn't limit the request body size on the /changes webhook endpoint

Mattermost Plugins versions =2.1.3.0 fail to limit the request body size on the /changes webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00611...

GHSA-X274-8QFC-HRGF Mattermost MS Teams plugin doesn't limit the request body size on the /lifecycle webhook endpoint

Mattermost Plugins versions =2.3.1 fail to limit the request body size on the /lifecycle webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00610...

CVE-2026-24661

Mattermost Plugins versions =2.1.3.0 fail to limit the request body size on the /changes webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00611...

CVE-2026-21388

Mattermost Plugins versions =2.3.1 fail to limit the request body size on the /lifecycle webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00610...

CVE-2026-24661

Mattermost Plugins versions =2.1.3.0 fail to limit the request body size on the /changes webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00611...

CVE-2026-24661 Unbounded Request Body Read in MS Teams Plugin {{/changes}} Webhook Endpoint

Mattermost Plugins versions =2.1.3.0 fail to limit the request body size on the /changes webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00611...