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

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

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-2026-6346 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...

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

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...

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 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...

EUVD-2026-30760

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 Fail to enforce slash command trigger-word uniqueness during command updates which allows an authenticated team member with Manage Own Slash Commands permission to hijack and impersonate existing system or custom slash...

CVE-2026-28732 Slash command trigger-word update allowed command hijacking

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 Fail to enforce slash command trigger-word uniqueness during command updates which allows an authenticated team member with Manage Own Slash Commands permission to hijack and impersonate existing system or custom slash...