The remote host is missing an update to wmaker announced via advisory DSA 074-1.
Alban Hertroys found a buffer overflow in Window Maker (a popular window manager for X). The code that handles titles in the window list menu did not check the length of the title when copying it to a buffer. Since applications will set the title using untrusted data (for example web browsers will set the title of their window to the title of the web-page being shown) this could be exploited remotely. This has been fixed in version 0.61.1-4.1 of the Debian package, and upstream version 0.65.1.