The remote host is missing an update to libapache-mod-dav announced via advisory DSA 558-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20558-1

Julian Reschke reported a problem in mod_dav of Apache 2 in connection with a NULL pointer dereference. When running in a threaded model, especially with Apache 2, a segmentation fault can take out a whole process and hence create a denial of service for the whole server. For the stable distribution (woody) this problem has been fixed in version 1.0.3-3.1. For the unstable distribution (sid) this problem has been fixed in version 1.0.3-10 of libapache-mod-dav and in version 2.0.51-1 of Apache 2. We recommend that you upgrade your mod_dav packages.