CVE-2026-18799

Mattermost versions 11.10.x = 11.10.0, 11.7.x = 11.7.9, 11.9.x = 11.9.1, 11.8.x = 11.8.5 fail to restrict Slack import account binding to system administrator-initiated imports which allows an authenticated attacker with team admin privileges to force-add existing Mattermost users to their team a...

CVE-2026-18799

Mattermost Server versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, and 11.8.x

EUVD-2026-102751

Mattermost versions 11.10.x = 11.10.0, 11.7.x = 11.7.9, 11.9.x = 11.9.1, 11.8.x = 11.8.5 fail to restrict Slack import account binding to system administrator-initiated imports which allows an authenticated attacker with team admin privileges to force-add existing Mattermost users to their team a...

CVE-2026-18799 Mattermost Server fails to restrict Slack import account binding, allowing team admins to forge posts as existing users

Mattermost versions 11.10.x = 11.10.0, 11.7.x = 11.7.9, 11.9.x = 11.9.1, 11.8.x = 11.8.5 fail to restrict Slack import account binding to system administrator-initiated imports which allows an authenticated attacker with team admin privileges to force-add existing Mattermost users to their team a...

CVE-2026-18799: Missing Authorization

Mattermost versions 11.10.x = 11.10.0, 11.7.x = 11.7.9, 11.9.x = 11.9.1, 11.8.x = 11.8.5 fail to restrict Slack import account binding to system administrator-initiated imports which allows an authenticated attacker with team admin privileges to force-add existing Mattermost users to their team a...

Insufficiently Protected Credentials

Overview Affected versions of this package are vulnerable to Insufficiently Protected Credentials via the Slack import process. An attacker can gain unauthorized access to user accounts by obtaining disclosed passwords and impersonating users. Remediation Upgrade...

Insufficiently Protected Credentials

Overview Affected versions of this package are vulnerable to Insufficiently Protected Credentials via the Slack import process. An attacker can gain unauthorized access to user accounts by obtaining disclosed passwords and impersonating users. Remediation Upgrade...

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 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 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...

Improper Authentication

github.com/mattermost/mattermost-server is vulnerable to improper authentication. The vulnerability is due to failure to validate email ownership during the Slack import process, which allows an attacker to create verified user accounts with arbitrary email domains and bypass email-based team...

SUSE CVE-2025-41410

Mattermost versions 10.10.x = 10.10.2, 10.5.x = 10.5.10, 10.11.x = 10.11.2 fail to validate email ownership during Slack import process which allows attackers to create verified user accounts with arbitrary email domains via malicious Slack import data to bypass email-based team access restrictio...

Mattermost Server 10.5.x < 10.5.11 / 10.10.x < 10.10.3 / 10.11.x 10.11.3 / 10.12.0 Missing Authorization (MMSA-2025-00525)

The version of Mattermost Server installed on the remote host is affected by a vulnerability as referenced in the MMSA-2025-00525 advisory. - Mattermost versions 10.10.x = 10.10.2, 10.5.x = 10.5.10, 10.11.x = 10.11.2 fail to validate email ownership during Slack import process which allows...

CVE-2025-41410

Mattermost versions 10.10.x = 10.10.2, 10.5.x = 10.5.10, 10.11.x = 10.11.2 fail to validate email ownership during Slack import process which allows attackers to create verified user accounts with arbitrary email domains via malicious Slack import data to bypass email-based team access restrictio...

Missing Authorization

Overview Affected versions of this package are vulnerable to Missing Authorization via the Slack import functionality. An attacker can create verified user accounts with arbitrary email domains by submitting malicious import data to bypass email-based team access restrictions. Remediation Upgrade...

Mattermost has a Missing Authorization vulnerability

Mattermost versions 10.10.x = 10.10.2, 10.5.x = 10.5.10, 10.11.x = 10.11.2 fail to validate email ownership during Slack import process which allows attackers to create verified user accounts with arbitrary email domains via malicious Slack import data to bypass email-based team access restrictio...

Missing Authorization

Overview Affected versions of this package are vulnerable to Missing Authorization via the Slack import functionality. An attacker can create verified user accounts with arbitrary email domains by submitting malicious import data to bypass email-based team access restrictions. Remediation Upgrade...

Missing Authorization

Overview Affected versions of this package are vulnerable to Missing Authorization via the Slack import functionality. An attacker can create verified user accounts with arbitrary email domains by submitting malicious import data to bypass email-based team access restrictions. Remediation Upgrade...

Missing Authorization

Overview github.com/mattermost/mattermost-server is an open source Slack-alternative in Golang and React. Affected versions of this package are vulnerable to Missing Authorization via the Slack import functionality. An attacker can create verified user accounts with arbitrary email domains by...