The convert extension in Mercurial before 3.8 might allow context-dependent attackers to execute arbitrary code via a crafted git repository name.
https://www.mercurial-scm.org/wiki/WhatsNew#Mercurial_3.8_.2F_3.8.1_.282016-5-1.29
https://selenic.com/hg/rev/a56296f55a5e
https://security.gentoo.org/glsa/201612-19
http://www.slackware.com/security/viewer.php?l=slackware-security&y=2016&m=slackware-security.533255
http://www.securityfocus.com/bid/90536
http://www.debian.org/security/2016/dsa-3570
http://lists.opensuse.org/opensuse-updates/2016-05/msg00082.html