CVE-2014-9489: Remote Code Execution

In vulnerable versions of the gem, searching for the string -O<arbitrary command> or --open-files-in-pager <arbritary command> in the wiki’s search field will execute an arbitrary shell command. However, this will only work if the string “master” (or more precisely, the name of the git branch that gollum is using) is found in one of the wiki’s files: “master” is then interpreted as the search query, -O<arbitary code> as a command line option to git grep.