CVE-2026-13311: shell-quote: Quadratic-complexity Denial of Service in `parse()` (CWE-407)

shell-quote’s parse() finalizes its token list with a reduce that uses Array.prototype.concat as the accumulator. Each prev.concat(arg) copies the entire growing array, so parse() runs in O(n²) in the number of tokens. An unauthenticated attacker who can submit a string to any code path that calls parse() on it can block the single-threaded Node.js event loop for tens of seconds with a small input — a denial of service. The trigger needs no shell metacharacters (plain space-separated words suffice), so input filters that only screen for ;, |, $, or backticks do not help.