The remote host is missing an update to libtasn1-3 announced via advisory DSA 2440-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202440-1

Matthew Hall discovered that many callers of the asn1_get_length_der function did not check the result against the overall buffer length before processing it further. This could result in out-of-bounds memory accesses and application crashes. Applications using GNUTLS are exposed to this issue. For the stable distribution (squeeze), this problem has been fixed in version 2.7-1+squeeze+1. For the unstable distribution (sid), this problem has been fixed in version 2.12-1. We recommend that you upgrade your libtasn1-3 packages.