zbateson/mail-mime-parser is a mail mime parser alternative to PHP's imap* functions and Pear libraries for reading messages in Internet Message Format RFC 822. Prior to version 3.0.6 and 4.0.2, CRLF (carriage-return / line-feed) header injection (CWE-93) affecting any application that uses this library to build or forward MIME messages with an attacker-influenced attachment filename. Attachment filenames are interpolated into the Content-Type and Content-Disposition header values without stripping CR/LF, so a filename containing \r\n serializes as one or more additional, attacker-controlled header lines (for example a forged Bcc: that silently exfiltrates a copy of the outgoing message). The untrusted filename can come directly from parsed inbound mail, so no local construction is…