=== baseline-repro on 6.5-DEVELOPMENT #0 (unpatched) ===
$ sysctl -n kern.version | head -1
DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026

$ cc -O2 -o make_crafted_iso make_crafted_iso.c && ./make_crafted_iso crafted.iso
DF-0853: wrote crafted.iso (204800 bytes)

$ vnconfig -c vn0 crafted.iso; mount -t cd9660 -o ro /dev/vn0 /mnt/df0853
MOUNT_RC=0

$ dmesg | tail -3
swap low/high-water marks set to 41940/62910
vn0: MBR magic not found; assume a COMPATIBILITY_SLICE (s0)
cd9660: High Sierra Format                 <-- TYPE CONFUSION (Standard PVD misclassified as High Sierra)
=== baseline-high-sierra-count: 1 ===