Time-of-check Time-of-use (TOCTOU) Race Condition
Flysystem is an open source file storage library for PHP. The whitespace normalisation using removes any unicode whitespace. Under certain specific conditions this could potentially allow a malicious user to execute code remotely. The conditions are: A user is allowed to supply the path or filename of an uploaded file, the supplied path or filename is not checked against unicode chars, the supplied pathname checked against an extension deny-list, not …