According to Python Security Advisory PSF-2005-001,
The Python development team has discovered a flaw in
the SimpleXMLRPCServer library module which
can give remote attackers access to internals of the
registered object or its module or possibly other modules.
The flaw only affects Python XML-RPC servers that use the
register_instance() method to register an object
without a _dispatch() method. Servers using
only register_function() are not affected.
On vulnerable XML-RPC servers, a remote attacker may
be able to view or modify globals of the module(s)
containing the registered instance's class(es), potentially
leading to data loss or arbitrary code execution. If the
registered object is a module, the danger is particularly
serious. For example, if the registered module imports
the os module, an attacker could invoke the
os.system() function.
Note: This vulnerability affects your
system only if you're running
SimpleXMLRPCServer-based server. This isn't
harmful at all if you don't run any internet server written
in Python or your server doesn't serve in XML-RPC protocol.