gitoxide-core does not neutralize special characters for terminals

Summary

The gix and ein commands write pathnames and other metadata literally to terminals, even if they contain characters terminals treat specially, including ANSI escape sequences. This sometimes allows an untrusted repository to misrepresent its contents and to alter or concoct error messages.

Details

gitoxide-core, which provides most underlying functionality of the gix and ein commands, does not neutralize newlines, backspaces, or control characters—including those that form ANSI escape sequences—that appear in a repository's paths, author and committer names, commit messages, or other metadata. Such text may be written as part of the output of a command, as well as appearing in error messages when an operation fails.

ANSI escape sequences are of particular concern because, when printed to a terminal, they can change colors, including to render subsequent text unreadable; reposition the cursor to write text in a different location, including where text has already been written; clear the terminal; set the terminal title-bar text to arbitrary values; render the terminal temporarily unusable; and other such operations.

The effect is mostly an annoyance. But the author of a malicious repository who can predict how information from the repository may be accessed can cause files in the repository to be concealed or otherwise misrepresented, as well as rewrite all or part of error messages, or mimic error messages convincingly by repositioning the curso…