MongoDB Database Tools mongorestore incorrectly URL-decodes an original collection name read from metadata when the corresponding dump filename has been truncated. A database user who can create and populate a suitably encoded collection can cause a later authorized directory restore to write those documents into a different collection that the user cannot modify directly. When both collection names resolve to the same destination, backed-up documents may be omitted; use of --drop can also replace the unintended destination collection. Exploitation requires an operator to restore the affected collection from a directory dump with write access to the destination. This issue affects MongoDB Database Tools versions 100.0.2 through versions before 100.20.1.