diff -up vim80/src/charset.c.cve4193 vim80/src/charset.c
--- vim80/src/charset.c.cve4193 2022-01-12 14:49:08.710592947 +0100
+++ vim80/src/charset.c 2022-01-12 14:49:47.594705863 +0100
@@ -1291,10 +1291,15 @@ getvcol(
posptr = NULL; /* continue until the NUL */
else
{
- /* Special check for an empty line, which can happen on exit, when
- * ml_get_buf() always returns an empty string. */
- if (*ptr == NUL)
- pos->col = 0;
+ colnr_T i;
+
+ // In a few cases the position can be beyond the end of the line.
+ for (i = 0; i < pos->col; ++i)
+ if (ptr[i] == NUL)
+ {
+ pos->col = i;
+ break;
+ }
posptr = ptr + pos->col;
#ifdef FEAT_MBYTE
if (has_mbyte)
diff -up vim80/src/testdir/test_regexp_latin.vim.cve4193 vim80/src/testdir/test_regexp_latin.vim
--- vim80/src/testdir/test_regexp_latin.vim.cve4193 2022-01-12 14:49:08.710592947 +0100
+++ vim80/src/testdir/test_regexp_latin.vim 2022-01-12 14:50:45.186873107 +0100
@@ -72,3 +72,11 @@ func Test_backref()
call assert_fails('call search("\\%#=2\\(e\\1\\)")', 'E65:')
bwipe!
endfunc
+
+func Test_using_invalid_visual_position()
+ " this was going beyond the end of the line
+ new
+ exe "norm 0o000\<Esc>0\<C-V>$s0"
+ /\%V
+ bwipe!
+endfunc