Dictionary sort corresponds to the intended behaviour. > echo -e "abc\n123\n456\nCVE-2011-234\nAbc\ndef\nCVE-2024-123" | sort --debug > -dfu
123 ___ 456 ___ abc ___ CVE-2011-234 ____________ CVE-2024-123 ____________ def ___ By comparison, human (-h) and numeric (-n) sort cause data loss: > echo -e "abc\n123\n456\nCVE-2011-234\nAbc\ndef\nCVE-2024-123" | sort --debug > -hu sort: note numbers use ‘.’ as a decimal point in this locale abc ^ no match for key 123 ___ 456 ___ If I were the author of gnu sort, I would delete the -h and -n options.