Race condition in the xdg.BaseDirectory.get_runtime_dir function in python-xdg 0.25 allows local users to overwrite arbitrary files by pre-creating /tmp/pyxdg-runtime-dir-fallback-victim to point to a victim-owned location, then replacing it with a symlink to an attacker-controlled location once the get_runtime_dir function is called.
https://exchange.xforce.ibmcloud.com/vulnerabilities/90618
http://www.securityfocus.com/bid/65042
http://www.openwall.com/lists/oss-security/2014/01/21/4