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-2026-6333

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-2026-6333

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

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 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 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-2026-6345

Mattermost advisory CVE-2026-6345 affects Mattermost versions 11.4.x ≤ 11.4.3, 11.5.x ≤ 11.5.1 and 10.11.x ≤ 10.11.13. The issue is described as failing to prevent disclosure of created user passwords during the Slack import process, which could allow a malicious actor to impersonate a user using...

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

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...

EUVD-2026-30756

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...

CVE-2026-6346

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to sanitize sensitive configuration fields before including them in support packet generation, which allows a Mattermost System Admin or any party with access to a support packet to obtain sensitive credentials in...

CVE-2026-6346 Sensitive credentials exposed in plaintext in Mattermost support packets

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to sanitize sensitive configuration fields before including them in support packet generation, which allows a Mattermost System Admin or any party with access to a support packet to obtain sensitive credentials in...

CVE-2026-6346

Mattermost has a vulnerability in support packet generation where sensitive configuration fields are not sanitized. This affects Mattermost versions 11.5.x up to 11.5.1, 10.11.x up to 10.11.13, and 11.4.x up to 11.4.3. The root cause is inclusion of unsanitized sensitive configuration data in sup...

EUVD-2026-30754

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to sanitize sensitive configuration fields before including them in support packet generation, which allows a Mattermost System Admin or any party with access to a support packet to obtain sensitive credentials in...

CVE-2026-6346 Sensitive credentials exposed in plaintext in Mattermost support packets

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to sanitize sensitive configuration fields before including them in support packet generation, which allows a Mattermost System Admin or any party with access to a support packet to obtain sensitive credentials in...

CVE-2026-6346 Sensitive credentials exposed in plaintext in Mattermost support packets

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to sanitize sensitive configuration fields before including them in support packet generation, which allows a Mattermost System Admin or any party with access to a support packet to obtain sensitive credentials in...