diff -up vim82/src/errors.h.cve1420 vim82/src/errors.h
--- vim82/src/errors.h.cve1420	2022-04-25 16:01:03.559985019 +0200
+++ vim82/src/errors.h	2022-04-25 16:01:58.113332024 +0200
@@ -383,3 +383,7 @@ EXTERN char e_cannot_use_default_values_
 	INIT(= N_("E1172: Cannot use default values in a lambda"));
 EXTERN char e_resulting_text_too_long[]
 	INIT(= N_("E1240: Resulting text too long"));
+#ifdef FEAT_EVAL
+EXTERN char e_string_or_function_required_for_arrow_parens_expr[]
+	INIT(= N_("E1275: String or function required for ->(expr)"));
+#endif
diff -up vim82/src/eval.c.cve1420 vim82/src/eval.c
--- vim82/src/eval.c.cve1420	2022-04-25 16:01:03.560985007 +0200
+++ vim82/src/eval.c	2022-04-25 16:14:11.746600369 +0200
@@ -3718,13 +3718,20 @@ eval_lambda(
 	if (**arg != ')')
 	{
 	    emsg(_(e_missing_close));
-	    ret = FAIL;
+	    return FAIL;
+	}
+	if (rettv->v_type != VAR_STRING && rettv->v_type != VAR_FUNC
+					       && rettv->v_type != VAR_PARTIAL)
+	{
+	    emsg(_(e_string_or_function_required_for_arrow_parens_expr));
+	    return FAIL;
 	}
 	++*arg;
     }
     if (ret != OK)
 	return FAIL;
-    else if (**arg != '(')
+
+    if (**arg != '(')
     {
 	if (verbose)
 	{
diff -up vim82/src/testdir/test_lambda.vim.cve1420 vim82/src/testdir/test_lambda.vim
--- vim82/src/testdir/test_lambda.vim.cve1420	2022-04-25 16:01:03.560985007 +0200
+++ vim82/src/testdir/test_lambda.vim	2022-04-25 16:17:01.694886566 +0200
@@ -64,6 +64,10 @@ function Test_lambda_fails()
   call assert_fails('echo {a, a -> a + a}(1, 2)', 'E853:')
   call assert_fails('echo {a, b -> a + b)}(1, 2)', 'E451:')
   echo assert_fails('echo 10->{a -> a + 2}', 'E107:')
+  call assert_fails('eval 0->(3)()', "E1275:")
+  call assert_fails('eval 0->([3])()', "E1275:")
+  call assert_fails('eval 0->({"a": 3})()', "E1275:")
+  call assert_fails('eval 0->(xxx)()', "E121:")
 endfunc
 
 func Test_not_lamda()