Package Instance

undici Denial of Service attack via bad certificate data
### Impact

Applications that use undici to implement a webhook-like system are vulnerable. If the attacker set up a server with an invalid certificate, and they can force the application to call the webhook repeatedly, then they can cause a memory leak. 

### Patches

This has been patched in https://github.com/nodejs/undici/pull/4088.

### Workarounds

If a webhook fails, avoid keep calling it repeatedly.

### References

Reported as: https://github.com/nodejs/undici/issues/3895

CRLF Injection in Nodejs ‘undici’ via host
Undici is an HTTP/1.1 client for Node.js. Starting with version 2.0.0 and prior to version 5.19.1, the undici library does not protect `host` HTTP header from CRLF injection vulnerabilities. This issue is patched in Undici v5.19.1. As a workaround, sanitize the `headers.host` string before passing to undici.

`undici.request` vulnerable to SSRF using absolute URL on `pathname`
### Impact

`undici` is vulnerable to SSRF (Server-side Request Forgery) when an application takes in **user input** into the `path/pathname` option of `undici.request`.

If a user specifies a URL such as `http://127.0.0.1` or `//127.0.0.1`

```js
const undici = require("undici")
undici.request({origin: "http://example.com", pathname: "//127.0.0.1"})
```

Instead of processing the request as `http://example.org//127.0.0.1` (or `http://example.org/http://127.0.0.1` when `http://127.0.0.1 is used`), it actually processes the request as `http://127.0.0.1/` and sends it to `http://127.0.0.1`.

If a developer passes in user input into `path` parameter of `undici.request`, it can result in an _SSRF_ as they will assume that the hostname cannot change, when in actual fact it can change because the specified path parameter is combined with the base URL.

### Patches

This issue was fixed in `undici@5.8.1`.

### Workarounds

The best workaround is to validate user input before passing it to the `undici.request` call.

## For more information
If you have any questions or comments about this advisory:

- Open an issue in [undici repository](https://github.com/nodejs/undici/issues)
- To make a report, follow the [SECURITY](https://github.com/nodejs/node/blob/HEAD/SECURITY.md) document

Undici has Unhandled Exception in WebSocket Client Due to Invalid server_max_window_bits Validation
### Impact

The undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the `server_max_window_bits` parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range `server_max_window_bits` value (outside zlib's valid range of 8-15). When the server subsequently sends a compressed frame, the client attempts to create a zlib InflateRaw instance with the invalid windowBits value, causing a synchronous RangeError exception that is not caught, resulting in immediate process termination.

The vulnerability exists because:

1. The `isValidClientWindowBits()` function only validates that the value contains ASCII digits, not that it falls within the valid range 8-15
2. The `createInflateRaw()` call is not wrapped in a try-catch block
3. The resulting exception propagates up through the call stack and crashes the Node.js process

### Patches
_Has the problem been patched? What versions should users upgrade to?_

### Workarounds
_Is there a way for users to fix or remediate the vulnerability without upgrading?_

Exposure of Sensitive Information to an Unauthorized Actor
Undici is an HTTP/1.1 client written from scratch for Node.js. Prior to version 5.26.2, Undici already cleared Authorization headers on cross-origin redirects, but does not clear `Cookie` headers. By design, `cookie` headers are forbidden request headers, disallowing them to be set in RequestInit.headers in browser environments. Since undici handles headers more liberally than the spec, there was a disconnect from the assumptions the spec made, and undici's implementation of fetch. As such this may lead to accidental leakage of cookie to a third-party site or a malicious attacker who can control the redirection target (ie. an open redirector) to leak the cookie to the third party site. This was patched in version 5.26.2. There are no known workarounds.

Undici has an HTTP Request/Response Smuggling issue
### Impact

Undici allows duplicate HTTP `Content-Length` headers when they are provided in an array with case-variant names (e.g., `Content-Length` and `content-length`). This produces malformed HTTP/1.1 requests with multiple conflicting `Content-Length` values on the wire.

**Who is impacted:**
  - Applications using `undici.request()`, `undici.Client`, or similar low-level APIs with headers passed as flat arrays
  - Applications that accept user-controlled header names without case-normalization

**Potential consequences:**
  - **Denial of Service**: Strict HTTP parsers (proxies, servers) will reject requests with duplicate `Content-Length` headers (400 Bad Request)
  - **HTTP Request Smuggling**: In deployments where an intermediary and backend interpret duplicate headers inconsistently (e.g., one uses the first value, the other uses the last), this can enable request smuggling attacks leading to ACL bypass, cache poisoning, or credential hijacking

### Patches

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

### Workarounds

  If upgrading is not immediately possible:

  1. **Validate header names**: Ensure no duplicate `Content-Length` headers (case-insensitive) are present before passing headers to undici
  2. **Use object format**: Pass headers as a plain object (`{ 'content-length': '123' }`) rather than an array, which naturally deduplicates by key
  3. **Sanitize user input**: If headers originate from user input, normalize header names to lowercase and reject duplicates

Undici has CRLF Injection in undici via `upgrade` option
### 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)
})
```

Nodejs ‘undici’ vulnerable to CRLF Injection via Content-Type
### Impact

`=< undici@5.8.0` users are vulnerable to _CRLF Injection_ on headers when using unsanitized input as request headers, more specifically, inside the `content-type` header.

Example:

```
import { request } from 'undici'

const unsanitizedContentTypeInput =  'application/json\r\n\r\nGET /foo2 HTTP/1.1'

await request('http://localhost:3000, {
    method: 'GET',
    headers: {
      'content-type': unsanitizedContentTypeInput
    },
})
```

The above snippet will perform two requests in a single `request` API call:

1) `http://localhost:3000/`
2) `http://localhost:3000/foo2`

### Patches

This issue was patched in Undici v5.8.1

### Workarounds

Sanitize input when sending content-type headers using user input.

## For more information
If you have any questions or comments about this advisory:

- Open an issue in [undici repository](https://github.com/nodejs/undici/issues)
- To make a report, follow the [SECURITY](https://github.com/nodejs/node/blob/HEAD/SECURITY.md) document