CVE-2026-90929: File Browser 2.5.0 Directory Deletion via Upload Failure Cleanup

Vulnerability summary

CVE-2026-90929 is a high (CVSS 8.1) Incorrect Authorization vulnerability in filebrowser. EPSS estimates a 0.44% chance of exploitation in the next 30 days, higher than 37.9% of scored vulnerabilities.

Timeline

1. 14-09-2026
   PublishedVulnerability first disclosed.
2. 14-09-2026
   Last modifiedVulnerability information updated.

Description

File Browser versions >= 2.5.0 and <= 2.63.23 contain an incorrect authorization flaw in the direct-upload endpoint (resourcePostHandler in http/resource.go). Unlike the TUS upload handler, the direct-upload handler does not reject a target that is an existing directory; a POST with ?override=true aimed at a directory fails inside writeFile (a directory cannot be opened for writing) and the failure-cleanup path then calls Fs.RemoveAll on the request path, recursively deleting the entire tree. This cleanup is gated by neither the Perm.Delete permission nor the checkDescendants rule walk applied by the delete and patch handlers, so an authenticated non-administrator holding only the default Create and Modify permissions can delete directories they are not authorized to delete, including rule-denied files within them. Deletion remains confined to the user's scope because ScopedFs.RemoveAll still enforces the scope guard. The faulty cleanup was introduced in v2.5.0; no patched version is available.

• CWE-863Incorrect AuthorizationThe product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.