GHSA-6v7q-wjvx-w8wg: basic-ftp: Incomplete CRLF Injection Protection Allows Arbitrary FTP Command Execution via Credentials and MKD Commands

basic-ftp’s CRLF injection protection (added in commit 2ecc8e2 for GHSA-chqc-8p9q-pq6q) is incomplete. Two code paths bypass the protectWhitespace() control character check: (1) the login() method directly concatenates user-supplied credentials into USER/PASS FTP commands without any validation, and (2) the _openDir() method sends an MKD command before cd() invokes protectWhitespace(), creating a TOCTOU bypass. Both vectors allow an attacker who controls input to inject arbitrary FTP commands into the control connection.