The remote host is missing an update to curl announced via advisory DSA 2271-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202271-1

Richard Silverman discovered that when doing GSSAPI authentication, libcurl unconditionally performs credential delegation. This hands the server a copy of the client's security credentials, allowing the server to impersonate the client to any other using the same GSSAPI mechanism. This is obviously a very sensitive operation, which should only be done when the user explicitly so directs. For the oldstable distribution (lenny), this problem has been fixed in version 7.18.2-8lenny5. For the stable distribution (squeeze), this problem has been fixed in version 7.21.0-2. For the testing distribution (wheezy), this problem has been fixed in version 7.21.6-2. For the unstable distribution (sid), this problem has been fixed in version 7.21.6-2. We recommend that you upgrade your curl packages.