Format string vulnerability in the print_proxies function in bin/proxy.c in libproxy 0.3.1 might allow context-dependent attackers to cause a denial of service (crash) and possibly execute arbitrary code via format string specifiers in a proxy name, as demonstrated using the http_proxy environment variable or a PAC file.
https://exchange.xforce.ibmcloud.com/vulnerabilities/80340
https://euvd.enisa.europa.eu/vulnerability/EUVD-2012-5467
https://code.google.com/p/libproxy/source/detail?r=475
https://bugzilla.redhat.com/show_bug.cgi?id=883100