compose.php in SquirrelMail 1.4.22 calls unserialize for the $mailtodata value, which originates from an HTTP GET request. This is related to mailto.php.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-14932
Reference (s):
- https://www.openwall.com/lists/oss-security/2020/06/20/1