GHSA-4qpj-gxxg-jqg4: Swiftmailer Sendmail transport arbitrary shell execution

Severity: Critical

CVSS Score: 10

Prior to 5.2.1, the sendmail transport (`Swift_Transport_SendmailTransport`) was vulnerable to an arbitrary shell execution if the "From" header came from a non-trusted source and no "Return-Path" is configured. This has been fixed in 5.2.1. If you are using sendmail as a transport, you are encouraged to upgrade as soon as possible.