Hi, I was (also) fuzzing another piece of software and ran into the same issue. I believe I was able to narrow down the cause of the problem a little bit more.
Rather than it being caused by the specific combination of a backslash and an unquoted U+0720 character I found it can be caused by: 1. Either a backslash or a quoted subcommand (e.g. the substring "'foo'" in "'foo'bar"), and 2. A character whose utf-8 encoding includes the bytes 0xA0. In the case of U+0720, it's utf-8 encoding is '0xDD 0xA0'. One thing I noticed, and I can't say for sure if this is related, is that U+00A0 is the "No-Break Space" (NBSP) character. Since whitespace can have special meanings for shell input I figured it might be related. -- System Information: OS: debian_version: 'bookworm/sid' (cat /etc/debian_version) I'm running csh version 20110502-7 on Ubuntu 22.04.1 LTS, amd64 (x86_64) architecture, libbsd0 v0.11.5-1, libc6 v2.35-0ubuntu3.1
