Pyrofork is a modern, asynchronous MTProto API framework. Versions 2.3.68 and earlier do not properly sanitize filenames received from Telegram messages in the download_media method before using them in file path construction. When downloading media, if the user does not specify a custom filename (which is the common/default usage), the method falls back to using the file_name attribute from the media object. The attribute originates from Telegram's DocumentAttributeFilename and is controlled by the message sender. This issue is fixed in version 2.3.69.