APT 0.7.x before 0.7.25 and 0.8.x before 0.8.16, when using the apt-key net-update to import keyrings, relies on GnuPG argument order and does not check GPG subkeys, which might allow remote attackers to install altered packages via a man-in-the-middle (MITM) attack. NOTE: this vulnerability exists because of an incomplete fix for CVE-2012-3587.
seclists.org/fulldisclosure/2012/Jun/267
seclists.org/fulldisclosure/2012/Jun/271
seclists.org/fulldisclosure/2012/Jun/289
www.securityfocus.com/bid/54046
www.ubuntu.com/usn/USN-1475-1
www.ubuntu.com/usn/USN-1477-1
bugs.launchpad.net/ubuntu/+source/apt/+bug/1013128
bugs.launchpad.net/ubuntu/+source/apt/+bug/1013639
bugs.launchpad.net/ubuntu/+source/apt/+bug/1013681