pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.0, multiple pam_usb helper tools resolved external binaries through the PATH environment variable rather than using absolute paths. An attacker who can influence the process environment during PAM authentication or tool execution could substitute malicious binaries. The affected tools are pamusb-check (src/tmux.c), pamusb-conf (tools/pamusb-conf), and pamusb-keyring-unlock-gnome (tools/pamusb-keyring-unlock-gnome). This vulnerability is fixed in 0.9.0.
https://github.com/mcdope/pam_usb/security/advisories/GHSA-pp29-w28g-r9h9
https://github.com/mcdope/pam_usb/commit/993e73d8bebb1d8e62677388de3402b6ec36b600
https://github.com/mcdope/pam_usb/commit/52a1fd6413b7ffcc1a5b58ce432be42e7bf0dbd0
https://github.com/mcdope/pam_usb/commit/1ee8745920388df48d001a8e61ba629071557937