exim4 - format string vulnerability

It was discovered that Exim, the default mail transport agent in
Debian, uses DKIM data obtain from DNS directly in a format string,
potentially allowing malicious mail senders to execute arbitrary code.
(CVE-2011-1764)

The oldstable distribution (lenny) is not affected by this problem
because it does not contain DKIM support.

For the stable distribution (squeeze), this problem has been fixed in
version 4.72-6+squeeze1.

For the unstable distribution (sid), this problem has been fixed in
version 4.75-3.

We recommend that you upgrade your exim4 packages.