Git before 2.10.5, 2.11.x before 2.11.4, 2.12.x before 2.12.5, 2.13.x before 2.13.6, and 2.14.x before 2.14.2 uses unsafe Perl scripts to support subcommands such as cvsserver, which allows attackers to execute arbitrary OS commands via shell metacharacters in a module name. The vulnerable code is reachable via git-shell even without CVS support.

A flaw was found in the way the Git client handles "ssh://" URLs. A maliciously crafted "ssh://" URL would cause Git clients to run an arbitrary shell command. Such a URL could be generated by a malicious server, by a malicious users committing to an honest server (to attack another user of that server's repositories), or by a proxy server.