libssh2 - security update

Mariusz Ziulek reported that libssh2, a SSH2 client-side library, was
reading and using the SSH_MSG_KEXINIT packet without doing sufficient
range checks when negotiating a new SSH session with a remote server. A
malicious attacker could man in the middle a real server and cause a
client using the libssh2 library to crash (denial of service) or
otherwise read and use unintended memory areas in this process.

For the stable distribution (wheezy), this problem has been fixed in
version 1.4.2-1.1+deb7u1.

We recommend that you upgrade your libssh2 packages.