The socket backend of CUPS 1.3.2 was patched at the University of Rennes 1 to prevent from infinite loops when reading side-channel requests.
In backend/socket.c at line 375, replace:
tbytes = backendRunLoop(print_fd, device_fd, 0, NULL);
by:
// modif PA // tbytes = backendRunLoop(print_fd, device_fd, 1, side_cb); tbytes = backendRunLoop(print_fd, device_fd, 0, NULL);
(no callback is passed for side-channel reading).
Once the patch applied, run make install.