Mattermost Desktop 5.13.x < 5.13.6 / 6.x < 6.2.0 Multiple Vulnerabilities (MMSA-2026-00651 / MMSA-2026-00652)

The version of Mattermost Desktop installed on the remote host is affected by multiple vulnerabilities: - Mattermost Desktop App versions =6.1 5.5.13.0 fail to restrict the allow list of domains to which NTLM credentials were forwarded to in the Mattermost Desktop App which allows any user on a...

CVE-2026-8683

Mattermost Desktop App versions =6.1 5.5.13.0 fail to account for attempting to open extremely long URLs in the Mattermost Desktop App which allows a malicious server owner to crash the application via including a script to call window.open on a very large URL. Mattermost Advisory ID:...

CVE-2026-6517

Mattermost Desktop App versions =6.1 5.5.13.0 fail to restrict the allow list of domains to which NTLM credentials were forwarded to in the Mattermost Desktop App which allows any user on a server without the image proxy enabled to intercept other users credentials via embedding an image that...

CVE-2026-8683

Mattermost Desktop App

EUVD-2026-36732

Mattermost Desktop App versions =6.1 5.5.13.0 fail to account for attempting to open extremely long URLs in the Mattermost Desktop App which allows a malicious server owner to crash the application via including a script to call window.open on a very large URL. Mattermost Advisory ID:...

CVE-2026-8683 Overly long URLs crash the Mattermost Desktop App

Mattermost Desktop App versions =6.1 5.5.13.0 fail to account for attempting to open extremely long URLs in the Mattermost Desktop App which allows a malicious server owner to crash the application via including a script to call window.open on a very large URL. Mattermost Advisory ID:...

CVE-2026-6517 Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed

Mattermost Desktop App versions =6.1 5.5.13.0 fail to restrict the allow list of domains to which NTLM credentials were forwarded to in the Mattermost Desktop App which allows any user on a server without the image proxy enabled to intercept other users credentials via embedding an image that...

PT-2026-49243

Name of the Vulnerable Software and Affected Versions Mattermost Desktop App versions prior to 6.1 Mattermost Desktop App version 5.5.13.0 Description The application fails to properly handle attempts to open extremely long URLs. A malicious server owner can cause the application to crash by...

CVE-2026-4643

Mattermost Desktop App versions =6.1 6.0.1 5.4.13.0 fail to prevent server-rendered content from closing an underlying application view in the Mattermost Desktop App which allows a malicious server or plugin to crash the desktop client via invoking window.close in the renderer context, leading to...

CVE-2026-3471

Mattermost Desktop App versions =6.1 6.0.1 5.4.13.0 fail to prevent an invalid URL from loading in a pop-up window in the Mattermost Desktop App which allows a malicious server owner to repeated crash the application via calling window.open'javascript:alert';. Mattermost Advisory ID: MMSA-2026-00...

Mattermost Desktop < 5.13.5 / < 6.0.2 / < 6.1.1 Multiple Vulnerabilities (MMSA-2026-00618 / MMSA-2026-00633)

"The version of Mattermost Desktop installed on the remote host is affected by multiple vulnerabilities as referenced in the MMSA-2026-00618 and MMSA-2026-00633 advisories. - Mattermost Desktop App fails to prevent an invalid URL from loading in a pop-up window which allows a malicious server own...

CVE-2026-4643

Mattermost Desktop App versions =6.1 6.0.1 5.4.13.0 fail to prevent server-rendered content from closing an underlying application view in the Mattermost Desktop App which allows a malicious server or plugin to crash the desktop client via invoking window.close in the renderer context, leading to...

CVE-2026-3471

Mattermost Desktop App versions =6.1 6.0.1 5.4.13.0 fail to prevent an invalid URL from loading in a pop-up window in the Mattermost Desktop App which allows a malicious server owner to repeated crash the application via calling window.open'javascript:alert';. Mattermost Advisory ID: MMSA-2026-00...

CVE-2026-3471 Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop App

Mattermost Desktop App versions =6.1 6.0.1 5.4.13.0 fail to prevent an invalid URL from loading in a pop-up window in the Mattermost Desktop App which allows a malicious server owner to repeated crash the application via calling window.open'javascript:alert';. Mattermost Advisory ID: MMSA-2026-00...

EUVD-2026-30757

Mattermost Desktop App versions =6.1 6.0.1 5.4.13.0 fail to prevent an invalid URL from loading in a pop-up window in the Mattermost Desktop App which allows a malicious server owner to repeated crash the application via calling window.open'javascript:alert';. Mattermost Advisory ID: MMSA-2026-00...

CVE-2026-3471 Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop App

Mattermost Desktop App versions =6.1 6.0.1 5.4.13.0 fail to prevent an invalid URL from loading in a pop-up window in the Mattermost Desktop App which allows a malicious server owner to repeated crash the application via calling window.open'javascript:alert';. Mattermost Advisory ID: MMSA-2026-00...

CVE-2026-4643

Mattermost Desktop App versions ≤ 6.1, 6.0.1, and 5.4.13.0 are affected by a flaw where server-rendered content can invoke window.close() in the renderer context, causing the underlying application view to close and yielding a client‑level denial of service. Root cause: the app fails to prevent s...

CVE-2026-4643

Mattermost Desktop App versions =6.1 6.0.1 5.4.13.0 fail to prevent server-rendered content from closing an underlying application view in the Mattermost Desktop App which allows a malicious server or plugin to crash the desktop client via invoking window.close in the renderer context, leading to...

EUVD-2026-30758

Mattermost Desktop App versions =6.1 6.0.1 5.4.13.0 fail to prevent server-rendered content from closing an underlying application view in the Mattermost Desktop App which allows a malicious server or plugin to crash the desktop client via invoking window.close in the renderer context, leading to...

CVE-2026-4643 Calling window.close() from server-side content causes crash in the Mattermost Desktop App

Mattermost Desktop App versions =6.1 6.0.1 5.4.13.0 fail to prevent server-rendered content from closing an underlying application view in the Mattermost Desktop App which allows a malicious server or plugin to crash the desktop client via invoking window.close in the renderer context, leading to...