The remote host is missing an update to xorg announced via advisory DSA 2364-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202364-1

The Debian X wrapper enforces that the X server can only be started from a console. vladz discovered that this wrapper could be bypassed. The oldstable distribution (lenny) is not affected. For the stable distribution (squeeze), this problem has been fixed in version 7.5+8+squeeze1. For the unstable distribution (sid), this problem has been fixed in version 1:7.6+10. We recommend that you upgrade your xorg packages.