What causes "vm.runInNewContext is not supported in Workers" in DIYgod/RSSHub?

Do not call runInNewContext under Workers.

vm.runInNewContext is not supported in Workers

Error message

vm.runInNewContext is not supported in Workers

What it means

vmShim.runInNewContext() in lib/shims/node-module.ts throws — Workers cannot spin up a new isolated context for code execution. This is the functional-form counterpart to ScriptShim.runInNewContext and fails for the same runtime reason.

Source

Thrown at lib/shims/node-module.ts:68

    }
    runInContext() {
        throw new Error('vm.Script.runInContext is not supported in Workers');
    }
    runInNewContext() {
        throw new Error('vm.Script.runInNewContext is not supported in Workers');
    }
    runInThisContext() {
        throw new Error('vm.Script.runInThisContext is not supported in Workers');
    }
}

const vmShim = {
    createContext: (sandbox?: object) => sandbox || {},
    runInContext: () => {
        throw new Error('vm.runInContext is not supported in Workers');
    },
    runInNewContext: () => {
        throw new Error('vm.runInNewContext is not supported in Workers');
    },
    runInThisContext: () => {
        throw new Error('vm.runInThisContext is not supported in Workers');
    },
    Script: ScriptShim,
    isContext: () => false,
    compileFunction: () => {
        throw new Error('vm.compileFunction is not supported in Workers');
    },
};

// Child process shim (inline to avoid import cycle)
const child_process = {
    execSync: (_command: string): Buffer => Buffer.from(''),
    exec: () => {
        throw new Error('exec is not supported in Cloudflare Workers');
    },
    spawn: () => {

View on GitHub (pinned to bed535e087)

Solutions

Do not call runInNewContext under Workers.
Precompile the snippet at build time or replace with static logic.
Move the eval-dependent route to Node.

Example fix

// before
vm.runInNewContext(code, sandbox);
// after
const fn = precompiledFns[name]; // build-time map, no runtime eval

Defensive patterns

Strategy: validation

Validate before calling

const vmUsable = typeof process !== 'undefined' && !!process.versions?.node;
if (!vmUsable) {
  // skip vm.runInNewContext; precompile instead
}

Type guard

function isVmShimError(e: unknown): e is Error {
  return e instanceof Error && /not supported in Workers/.test(e.message);
}

Try / catch

try {
  if (vmUsable) vm.runInNewContext(code, sandbox);
  else return precompiledFns[name](data);
} catch (e) {
  if (isVmShimError(e)) return precompiledFns[name](data);
  throw e;
}

Prevention

Never sandbox-eval untrusted code under Workers.
Precompile to a function map at build time.
Keep per-call sandbox execution on Node.

When it happens

Trigger: Calling vm.runInNewContext(code, sandbox) under Workers; some bundlers/loaders and sandbox libraries use this form.

Common situations: Sandboxing third-party/untrusted code; polyfills that evaluate snippets per-call.

Related errors

AI-assisted analysis of DIYgod/RSSHub@bed535e087 (2026-08-12). Data as JSON: /api/errors/681d66e4fc82df40. Report an issue: GitHub.