CVE-2026-54414

FileRise before 3.16.0 is vulnerable to path traversal in the shared-folder upload endpoint (/api/folder/uploadToSharedFolder.php), leading to arbitrary file write and administrator account takeover. The upload filename is validated by FolderController with basename() and REGEXFILENAME, which permit URL-encoded sequences (the regex blocks / and \ but not %). The raw filename is then passed to UploadModel::handleUpload, where it is reconstructed as trim(urldecode(basename($fileName))), re-introducing path separators after validation (e.g. ..%2fusers%2fusers.txt becomes ../users/users.txt). UploadNamePolicy::isAllowedForWrite() applies basename() internally and therefore only evaluates the final component (users.txt), allowing the traversal sequence to pass the extension policy. The destination path is then used directly in moveuploadedfile() with no realpath containment check, allowing a write outside the intended upload directory. An attacker who possesses a valid, non-expired, upload-enabled shared-folder link/token (which are designed to be shared publicly) can overwrite users/users.txt to create an administrator account, resulting in unauthenticated admin takeover and, depending on configuration, remote code execution. Exploitation requires possession of a valid, non-expired, upload-enabled shared-folder link/token. This issue is fixed in 3.16.0, which URL-decodes before validation and rejects any path separators in the upload filename.