It was found that libcurl did not safely parse FTP URLs when using the CURLOPT_FTP_FILEMETHOD method. An attacker, able to provide a specially crafted FTP URL to an application using libcurl, could write a NULL byte at an arbitrary location, resulting in a crash or an unspecified behavior.
Preventing application from using non-default CURLOPT_FTP_FILEMETHOD will avoid triggering the vulnerable code.