Debian DSA-2826-1: Critical Denial Of Service Risk In Denyhosts

Helmut Grohne discovered that denyhosts, a tool preventing SSH
brute-force attacks, could be used to perform remote denial of service
against the SSH daemon. Incorrectly specified regular expressions used
to detect brute force attacks in authentication logs could be exploited
by a malicious user to forge crafted login names in order to make
denyhosts ban arbitrary IP addresses.

For the oldstable distribution (squeeze), this problem has been fixed in
version 2.6-7+deb6u2.

For the stable distribution (wheezy), this problem has been fixed in
version 2.6-10+deb7u2.

For the testing distribution (jessie), this problem has been fixed in
version 2.6-10.1.

For the unstable distribution (sid), this problem has been fixed in
version 2.6-10.1.

We recommend that you upgrade your denyhosts packages.

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: http://www.debian.org/security/