Shell-quoting bypasses defeat pattern-based command guards in 10 of 11 open-source coding agents (GuardFall)

Adversa AI·high signal

GuardFall is a universal shell injection flaw showing that decades-old shell-quoting tricks trivially bypass the regex/denylist command guards that nearly every open-source coding agent ships with — 10 of 11 tested agents fell. No formal CVE was assigned, which means most teams will never see it through normal vulnerability channels. The actionable conclusion is architectural: move enforcement from the model/prompt layer to the OS layer (seccomp, Landlock, gVisor, microVM), because any guard that reasons about command *strings* is defeated by quoting, and compositional attacks make per-command scanning obsolete.