The remote host is missing an update to the system as announced in the referenced advisory.

Update your system with the appropriate patches or software upgrades.

The following package is affected: dovecot CVE-2011-1929 lib-mail/message-header-parser.c in Dovecot 1.2.x before 1.2.17 and 2.0.x before 2.0.13 does not properly handle '\0' characters in header names, which allows remote attackers to cause a denial of service (daemon crash or mailbox corruption) via a crafted e-mail message.