Affected: npm: undici

### Impact

When an application passes user-controlled input to the `upgrade` option of `client.request()`, an attacker can inject CRLF sequences (`\r\n`) to:

1. Inject arbitrary HTTP headers 2. Terminate the HTTP request prematurely and smuggle raw data to non-HTTP services (Redis, Memcached, Elasticsearch)

The vulnerability exists because undici writes the `upgrade` value directly to the socket without validating for invalid header characters:

```javascript // lib/dispatcher/client-h1.js:1121 if (upgrade) { header += `connection: upgrade\r\nupgrade: ${upgrade}\r\n` } ```

### Patches

Patched in the undici version v7.24.0 and v6.24.0. Users should upgrade to this version or later.

### Workarounds

Sanitize the `upgrade` option string before passing to undici:

```javascript function sanitizeUpgrade(value) { if (/[\r\n]/.test(value)) { throw new Error('Invalid upgrade value') } return value }

client.request({ upgrade: sanitizeUpgrade(userInput) }) ```