kbx/keybox-search.c in GnuPG before 1.4.19, 2.0.x before 2.0.27, and 2.1.x before 2.1.2 does not properly handle bitwise left-shifts, which allows remote attackers to cause a denial of service (invalid read operation) via a crafted keyring file, related to sign extensions and "memcpy with overlapping ranges."
http://www.ubuntu.com/usn/usn-2554-1/
http://www.securityfocus.com/bid/72610