CVE-2026-90929: File Browser 2.5.0 Directory Deletion via Upload Failure Cleanup
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.
Affected Software
Event History
Frequently Asked Questions
Who can exploit this issue?
An authenticated non-administrator can exploit it if they have Create and Modify permissions, which are described as the default permissions. The affected versions are 2.5.0 through 2.63.23.
What does an attacker need to send to trigger the deletion?
The attacker needs to use the direct-upload endpoint with override=true and target an existing directory. The upload fails because the target is a directory, after which the failure-cleanup path recursively removes the requested path.
Does withholding Delete permission prevent exploitation?
No. The vulnerable cleanup path is not gated by the Perm.Delete permission and does not apply the checkDescendants rule walk used by normal delete and patch handlers.
How far can an unauthorized deletion reach?
Deletion can recursively remove the targeted directory tree, including files denied by descendant rules. It remains limited to the authenticated user's configured scope because ScopedFs.RemoveAll enforces the scope guard.
Is a patched version available?
No patched version is available according to the provided information.