diff -up ./src/programs/pkcheck.c.ori ./src/programs/pkcheck.c

--- ./src/programs/pkcheck.c.ori	2021-12-17 11:56:55.336675787 +0100

+++ ./src/programs/pkcheck.c	2021-12-17 12:08:19.736029380 +0100

@@ -362,6 +362,12 @@ main (int argc, char *argv[])

   local_agent_handle = NULL;

   ret = 126;

+  if (argc < 1)

+    {

+      help();

+      exit(1);

+    }

+

   g_type_init ();

   details = polkit_details_new ();

diff -up ./src/programs/pkexec.c.ori ./src/programs/pkexec.c

--- ./src/programs/pkexec.c.ori	2021-12-17 11:55:12.686171757 +0100

+++ ./src/programs/pkexec.c	2021-12-17 11:56:55.336675787 +0100

@@ -490,6 +490,17 @@ main (int argc, char *argv[])

   pid_t pid_of_caller;

   gpointer local_agent_handle;

+

+  /*

+   * If 'pkexec' is called wrong, just show help and bail out.

+   */

+  if (argc<1)

+    {

+      clearenv();

+      usage(argc, argv);

+      exit(1);

+    }

+

   ret = 127;

   authority = NULL;

   subject = NULL;

@@ -601,7 +612,15 @@ main (int argc, char *argv[])

           goto out;

         }

       g_free (path);

-      argv[n] = path = s;

+      path = s;

+

+      /* argc<2 and pkexec runs just shell, argv is guaranteed to be null-terminated.

+       * /-less shell shouldn't happen, but let's be defensive and don't write to null-termination

+       */

+      if (argv[n] != NULL)

+      {

+        argv[n] = path;

+      }

     }

   if (access (path, F_OK) != 0)

     {