Launchpad.net

CVE 2011-1947

fetchmail 5.9.9 through 6.3.19 does not properly limit the wait time after issuing a (1) STARTTLS or (2) STLS request, which allows remote servers to cause a denial of service (application hang) by acknowledging the request but not sending additional packets.

See the CVE page on Mitre.org for more details.