The _validaterepo function in sshpeer in Mercurial before 3.2.4 allows remote attackers to execute arbitrary commands via a crafted repository name in a clone command.
https://security.gentoo.org/glsa/201612-19
http://www.oracle.com/technetwork/topics/security/bulletinjul2015-2511963.html
http://www.debian.org/security/2015/dsa-3257
http://mercurial.selenic.com/wiki/WhatsNew
http://lists.opensuse.org/opensuse-updates/2015-03/msg00085.html