subrepo: set GIT_ALLOW_PROTOCOL to limit git clone protocols (SEC) CVE-2016-3068 (1/1) Git's git-remote-ext remote helper provides an ext:: URL scheme that allows running arbitrary shell commands. This feature allows implementing simple git smart transports with a single shell shell command. However, git submodules could clone arbitrary URLs specified in the .gitmodules file. This was reported as CVE-2015-7545 and fixed in git v2.6.1. However, if a user directly clones a malicious ext URL, the git client will still run arbitrary shell commands. Mercurial is similarly effected. Mercurial allows specifying git repositories as subrepositories. Git ext:: URLs can be specified as Mercurial subrepositories allowing arbitrary shell commands to be run on `hg clone ...`. The Mercurial community would like to thank Blake Burkhart for reporting this issue. The description of the issue is copied from Blake's report. This commit changes submodules to pass the GIT_ALLOW_PROTOCOL env variable to git commands with the same list of allowed protocols that git submodule is using. When the GIT_ALLOW_PROTOCOL env variable is already set, we just pass it to git without modifications.