CVE-2026-39942

A broken access control vulnerability was identified in the Directus file management API that allows authenticated users to overwrite files belonging to other users by manipulating the filename_disk parameter.

Details

The PATCH /files/{id} endpoint accepts a user-controlled filename_disk parameter. By setting this value to match the storage path of another user's file, an attacker can overwrite that file's content while manipulating metadata fields such as uploaded_by to obscure the tampering.

Mitigation

The filename_disk parameter should be treated as a server-controlled value. Uniqueness of storage paths must be enforced server-side, and filename_disk should be excluded from the fields users are permitted to update directly.

• Unauthorized File Overwrite: Attackers can replace legitimate files with malicious content, creating significant risk of malware propagation and data corruption.
• Remote Code Execution: If the storage backend is shared with the extensions location, attackers can deploy malicious extensions that execute arbitrary code when loaded.
• Data Integrity Compromise: Files can be tampered with or replaced without visible indication in the application interface.

CVE-2026-39942 has a CVSS score of 8.5 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (11.17.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-39942? CVE-2026-39942 is a high-severity security vulnerability in directus (npm), affecting versions < 11.17.0. It is fixed in 11.17.0.
2. How severe is CVE-2026-39942? CVE-2026-39942 has a CVSS score of 8.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of directus are affected by CVE-2026-39942? directus (npm) versions < 11.17.0 is affected.
4. Is there a fix for CVE-2026-39942? Yes. CVE-2026-39942 is fixed in 11.17.0. Upgrade to this version or later.
5. Is CVE-2026-39942 exploitable, and should I be worried? Whether CVE-2026-39942 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-39942 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-39942? Upgrade directus to 11.17.0 or later.