It was discovered that dkim-milter, an implementation of the DomainKeys Identified Mail protocol, may crash during DKIM verification if it encounters a specially-crafted or revoked public key record in DNS.
The old stable distribution (etch) does not contain dkim-milter packages.
For the stable distribution (lenny), this problem has been fixed in version 2.6.0.dfsg-1+lenny1.
For the unstable distribution (sid), this problem has been fixed in version 2.6.0.dfsg-2.
We recommend that you upgrade your dkim-milter packages.
MD5 checksums of the listed files are available in the original advisory.