CVE-2026-28417: fix OS command injection in netrw plugin via crafted
scp:// URIs by adding strict RFC1123 hostname validation and using
shellescape() for hostname and port values.
CVE-2026-28421: fix heap-buffer-overflow and SEGV in swap file recovery
by adding bounds checks on pe_page_count, pe_bnum, pe_old_lnum and
pe_line_count before descending into the block tree.