Race condition in the xdg.BaseDirectory.get_runtime_dir function in pyxdg 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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2014-1624
• https://exchange.xforce.ibmcloud.com/vulnerabilities/90618
• http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=736247
• http://www.openwall.com/lists/oss-security/2014/01/21/3
• http://www.openwall.com/lists/oss-security/2014/01/21/4
• takluyver/pyxdg@bd999c1
• https://web.archive.org/web/20200227194825/http://www.securityfocus.com/bid/65042
• https://github.com/pypa/advisory-database/tree/main/vulns/pyxdg/PYSEC-2014-95.yaml