CVE-2026-7521 in Mattermost
Summary
by MITRE • 07/28/2026
Mattermost versions 11.8.x <= 11.8.0, 11.7.x <= 11.7.3, 11.6.x <= 11.6.5, 10.11.x <= 10.11.20 fail to verify file deletion path which allows an admin with SAML system-console write permissions to delete arbitrary files outside the config directory from the server via the remove file endpoint.. Mattermost Advisory ID: MMSA-2026-00666
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Analysis
by VulDB Data Team • 07/28/2026
This vulnerability exists in Mattermost server versions across multiple release streams including 11.8.0, 11.7.3, 11.6.5, and 10.11.20 where the file deletion functionality lacks proper path validation mechanisms. The flaw specifically affects administrators who possess SAML system-console write permissions, creating a critical privilege escalation vector that allows malicious actors to execute unauthorized file operations beyond the intended configuration directory boundaries.
The technical implementation of this vulnerability stems from inadequate input sanitization within the remove file endpoint functionality. When administrators attempt to delete files through the system console interface, the application fails to properly validate or sanitize the file paths provided during the deletion request. This path traversal flaw enables attackers to manipulate the file deletion process and target arbitrary locations on the server filesystem, potentially compromising system integrity and data security.
The operational impact of this vulnerability extends beyond simple unauthorized file removal, as it provides attackers with persistent access to critical system resources. An attacker with SAML write permissions can exploit this weakness to delete essential configuration files, system binaries, or sensitive data repositories, potentially leading to service disruption, data loss, or complete system compromise. The vulnerability specifically targets the server's file system management capabilities rather than user data, making it particularly dangerous for maintaining system availability and integrity.
This vulnerability aligns with CWE-22 Path Traversal and follows patterns identified in ATT&CK technique T1059 Command and Scripting Interpreter where attackers can leverage system-level permissions to manipulate file systems. The flaw represents a classic authorization bypass issue where proper access controls should prevent deletion operations outside designated directories but fail to enforce such boundaries effectively.
Organizations should immediately implement mitigations including patching to the latest stable versions of Mattermost, implementing additional path validation checks in custom configurations, and restricting SAML system-console write permissions to only trusted administrators. Network segmentation and monitoring of file deletion activities through security information and event management systems can provide additional layers of defense against exploitation attempts. The vulnerability demonstrates the critical importance of input validation and proper access control implementation in enterprise collaboration platforms where administrative privileges can have far-reaching consequences across system infrastructure.