diff -up shadow-4.9/libmisc/prefix_flag.c.groupdel-fix-sigsegv-when-passwd-does-not-exist shadow-4.9/libmisc/prefix_flag.c
--- shadow-4.9/libmisc/prefix_flag.c.groupdel-fix-sigsegv-when-passwd-does-not-exist	2021-11-19 09:21:36.997091941 +0100
+++ shadow-4.9/libmisc/prefix_flag.c	2021-11-19 09:22:19.001341010 +0100
@@ -288,6 +288,9 @@ extern struct passwd* prefix_getpwent()
 	if(!passwd_db_file) {
 		return getpwent();
 	}
+	if (!fp_pwent) {
+		return NULL;
+	}
 	return fgetpwent(fp_pwent);
 }
 extern void prefix_endpwent()