The shell_quote function in python-gnupg 0.3.5 does not properly quote strings, which allows context-dependent attackers to execute arbitrary code via shell metacharacters in unspecified vectors, as demonstrated using "$(" command-substitution sequences, a different vulnerability than CVE-2014-1928. NOTE: this vulnerability exists because of an incomplete fix for CVE-2013-7323.
https://code.google.com/p/python-gnupg/
http://www.debian.org/security/2014/dsa-2946