CVE-2026-32759
Vulnérabilité moyenne dans filebrowser (filebrowser)
Description
File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. In versions on the 2.x branch prior to 2.33.8, the TUS resumable upload handler parses the Upload-Length header as a signed 64-bit integer without validating that the value is non-negative, allowing an authenticated user to supply a negative value that instantly satisfies the upload completion condition upon the first PATCH request. This causes the server to fire after_upload exec hooks with empty or partial files, enabling an attacker to repeatedly trigger any configured hook with arbitrary filenames and zero bytes written. The impact ranges from DoS through expensive processing hooks, to command injection amplification when combined with malicious filenames, to abuse of upload-driven workflows like S3 ingestion or database inserts. Even without exec hooks enabled, the negative Upload-Length creates inconsistent cache entries where files are marked complete but contain no data. All deployments using the TUS upload endpoint (/api/tus) are affected, with the enableExec flag escalating the impact from cache inconsistency to remote command execution. This feature has been disabled by default for all installations from v2.33.8 onwards, including for existent installations. To exploit this vulnerability, the instance administrator must turn on a feature and ignore all the warnings about known vulnerabilities.
Gravité et risque d'exploitation
CVE-2026-32759 obtient un score CVSS de 5.3/10, soit une gravité moyenne. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 2.25 %, ce qui la place devant 82.7 % des CVE référencées.
Que faire ?
- Vérifiez si filebrowser (versions < 2.33.8) est présent sur votre parc.
- Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
- À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
- Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.