apt - security update

Jakub Wilk discovered that APT, the high level package manager,
did not properly perform authentication checks for source packages
downloaded via “apt-get source”. This only affects use cases where
source packages are downloaded via this command; it does not
affect regular Debian package installation and upgrading.

For the stable distribution (wheezy), this problem has been fixed in
version 0.9.7.9+deb7u2.

For the unstable distribution (sid), this problem has been fixed in
version 1.0.4.

We recommend that you upgrade your apt packages.