PT-2026-48941

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 Mattermost fails to require role-management authorization when setting the scheme admin flag on group syncable link and patch endpoints, which allows a user with group-link permissions to escalate...

PT-2026-42751

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.2, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to validate the TIFF IFD offset in the image header before allocating memory, which allows authenticated users with file upload or posting permissions to cause a denial of service serve...

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...

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...

SUSE CVE-2026-25783

Mattermost versions 11.3.x = 11.3.0, 11.2.x = 11.2.2, 10.11.x = 10.11.10 fail to properly validate User-Agent header tokens which allows an authenticated attacker to cause a request panic via a specially crafted User-Agent header. Mattermost Advisory ID: MMSA-2026-00586...

CVE-2026-3115

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 apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint...

CVE-2026-3113 mmctl export download command doesn’t restrict permissions to created file to file owner

Mattermost versions 11.4.x = 11.4.0, 11.3.x = 11.3.1, 11.2.x = 11.2.3, 10.11.x = 10.11.11 fail to set permissions on downloaded bulk export which allows other local users on the server to be able to read contents of the bulk export.. Mattermost Advisory ID: MMSA-2026-00593...

EUVD-2026-12416

Mattermost versions 11.3.x = 11.3.0, 11.2.x = 11.2.2, 10.11.x = 10.11.10 fail to properly validate User-Agent header tokens which allows an authenticated attacker to cause a request panic via a specially crafted User-Agent header. Mattermost Advisory ID: MMSA-2026-00586...

EUVD-2026-12407

Mattermost versions 11.3.x = 11.3.0, 11.2.x = 11.2.2, 10.11.x = 10.11.10 fail to sanitize client-supplied post metadata which allows an authenticated attacker to spoof permalink embeds impersonating other users via crafted PUT requests to the post update API endpoint.. Mattermost Advisory ID:...

CVE-2026-25783

Mattermost versions 11.3.x = 11.3.0, 11.2.x = 11.2.2, 10.11.x = 10.11.10 fail to properly validate User-Agent header tokens which allows an authenticated attacker to cause a request panic via a specially crafted User-Agent header. Mattermost Advisory ID: MMSA-2026-00586...

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...

SUSE CVE-2017-18911

An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. The X.509 certificate validation can be skipped for a TLS-based e-mail server...

GHSA-3C9R-7F29-QP32 Mattermost fails to properly validate login method restrictions

Mattermost versions 11.1.x = 11.1.2, 10.11.x = 10.11.9, 11.2.x = 11.2.1 fail to properly validate login method restrictions which allows an authenticated user to bypass SSO-only login requirements via userID-based authentication. Mattermost Advisory ID: MMSA-2025-00548...

SUSE CVE-2017-18885

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It allows attackers to gain privileges by accessing unintended API endpoints on a user's behalf...

SUSE CVE-2025-12421

Mattermost versions 11.0.x = 11.0.2, 10.12.x = 10.12.1, 10.11.x = 10.11.4, 10.5.x = 10.5.12 fail to to verify that the token used during the code exchange originates from the same authentication flow, which allows an authenticated user to perform account takeover via a specially crafted email...

SUSE CVE-2025-13352

Mattermost versions 10.11.x = 10.11.6 and Mattermost GitHub plugin versions =2.4.0 fail to validate plugin bot identity in reaction forwarding which allows attackers to hijack the GitHub reaction feature to make users add reactions to arbitrary GitHub objects via crafted notification posts...

Privilege Context Switching Error

Overview Affected versions of this package are vulnerable to Privilege Context Switching Error in the current user session. An attacker can gain unauthorized access to files and subscribe to blocks belonging to other users by sending crafted requests as an authenticated user. Remediation Upgrade...

Mattermost 安全漏洞

Mattermost is an open source collaboration platform from Mattermost, Inc. in the United States. A security vulnerability exists in Mattermost versions 10.11.4 and prior to 10.11.x and 10.5.12 and prior to 10.5.x. The vulnerability stems from unvalidated user permissions and could lead to...

CVE-2025-55074

Mattermost versions 10.11.x = 10.11.3, 10.5.x = 10.5.11 fail to enforce access permissions on the Agents plugin which allows other users to determine when users had read channels via channel member objects...

CVE-2025-11776

Mattermost versions 11 fail to properly restrict access to archived channel search API which allows guest users to discover archived public channels via the /api/v4/teams/teamid/channels/searcharchived endpoint...