CVE-2026-3117

Mattermost Plugins versions =11.5 11.1.5 10.13.11 11.3.4.0 fail to properly check for permissions when processing commands in the Gitlab plugin which allows normal users to uninstall instances or setup webhook connections via the gitlab instance option or the /gitlab webhook option commands...

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-2026-3471 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-2026-3471 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

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 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...

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

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 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...

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...

CVE-2026-6333 SSRF via Host Header Spoofing in Custom Slash Commands

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost...

CVE-2026-6333

Mattermost versions 11.5.x <= 11.5.1 and 10.11.x

CVE-2026-6333 SSRF via Host Header Spoofing in Custom Slash Commands

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost...

EUVD-2026-30755

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost...

CVE-2026-6333 SSRF via Host Header Spoofing in Custom Slash Commands

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost...

CVE-2026-6333

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost...

CVE-2026-6345 Prevent password disclosure and force reset during Slack import

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail prevent disclosure of created user password which allows a malicious attacker to impersonate a user via the use of some of those passwords.. Mattermost Advisory ID: MMSA-2026-00614...

CVE-2026-6345 Prevent password disclosure and force reset during Slack import

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail prevent disclosure of created user password which allows a malicious attacker to impersonate a user via the use of some of those passwords.. Mattermost Advisory ID: MMSA-2026-00614...