The remote host is missing an update to openswan announced via advisory DSA 1898-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201898-1

It was discovered that the pluto daemon in the openswan, an implementation of IPSEC and IKE, could crash when processing a crafted X.509 certificate. For the old stable distribution (etch), this problem has been fixed in version 2.4.6+dfsg.2-1.1+etch2. For the stable distribution (lenny), this problem has been fixed in version 2.4.12+dfsg-1.3+lenny2. For the unstable distribution (sid), this problem has been fixed in version 2.6.22+dfsg-1. We recommend that you upgrade your openswan package.