CVE-2026-6541 in Mattermost
Summary
by MITRE • 07/13/2026
Mattermost versions 11.7.x <= 11.7.1, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to restrict metric configuration changes to the playbook being saved, which allows an authenticated user with team access to alter another user’s playbook metric settings via a crafted import or update request with a foreign metric ID. Mattermost Advisory ID: MMSA-2026-00653
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Analysis
by VulDB Data Team • 07/13/2026
This vulnerability represents a critical authorization bypass flaw in Mattermost's playbook management system that stems from inadequate input validation and privilege enforcement mechanisms. The issue affects multiple version streams including 11.7.1 and earlier, 11.6.4 and earlier, and 10.11.19 and earlier, indicating a widespread security gap within the platform's access control framework. The vulnerability specifically targets the playbook metric configuration functionality where the system fails to properly validate whether a user has authorization to modify metrics associated with playbooks they do not own.
The technical exploitation occurs through crafted import or update requests that contain foreign metric IDs, allowing authenticated users with basic team access to manipulate another user's playbook configurations. This represents a classic case of insufficient authorization checks where the system accepts external metric identifiers without verifying ownership or permission boundaries. The flaw enables arbitrary metric configuration changes that could potentially disrupt workflow automation, alter reporting data, or compromise the integrity of automated response procedures within the platform.
From an operational impact perspective, this vulnerability creates significant risks for organizations relying on Mattermost's playbook features for security orchestration and incident response. An attacker could modify critical metric settings to either disable important alerts, manipulate performance thresholds, or redirect automated actions to unintended targets. The ability to alter another user's playbook metrics without proper authorization undermines the integrity of security workflows and could lead to missed incidents or false positives in automated threat detection systems.
The vulnerability aligns with CWE-285 (Improper Authorization) and represents a specific implementation weakness where the system fails to enforce proper access controls during playbook metric configuration updates. This flaw intersects with ATT&CK technique T1566 (Phishing) and T1078 (Valid Accounts) as it could be leveraged by attackers who have gained initial access through other means to further escalate their privileges within the platform. Organizations using Mattermost for security operations centers or incident response teams face particular risk since playbook configurations often contain critical automation rules that govern system behavior during security events.
Mitigation strategies should include immediate patching of affected versions, implementation of additional input validation controls, and enhanced monitoring of playbook configuration changes. System administrators should review access controls for playbook management functions and consider implementing role-based access controls that more strictly enforce ownership boundaries. The platform should be configured to validate all metric identifiers against the current user's permissions before allowing any modifications to playbook configurations. Additionally, organizations should implement audit logging for all playbook import and update operations to detect unauthorized configuration changes and establish automated alerts for suspicious metric modification patterns.
This vulnerability demonstrates the importance of proper input validation and authorization enforcement in collaborative platforms where multiple users share access to shared resources. The flaw highlights how seemingly minor configuration management issues can create substantial security risks when combined with user privilege escalation opportunities within complex automation frameworks. Organizations should conduct comprehensive audits of their Mattermost implementations to identify similar authorization gaps that could be exploited by malicious actors seeking to manipulate automated response systems or compromise the integrity of shared security workflows.