GHSA-322x-v876-g883 @asymmetric-effort/nogginlessdom's Path Traversal in matchFileSnapshot allows arbitrary file write

Not scored Published 2 Jul 2026

Attackers can write arbitrary files via path traversal in snapshot updates, potentially compromising CI/CD pipelines and executing code.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is GHSA-322x-v876-g883?

GHSA-322x-v876-g883 is a path traversal vulnerability in @asymmetric-effort/nogginlessdom, published on 2 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

Summary

The matchFileSnapshot function in src/assertions/snapshots.ts accepted a filePath parameter with zero validation. When snapshot update mode was active (UPDATE_SNAPSHOTS=1 or setUpdateMode('all')), an attacker who controls test input could write arbitrary content to any filesystem path the process has write access to, including creating intermediate directories.

Affected Code

File: src/assertions/snapshots.ts, lines 732-769

export function matchFileSnapshot(actual: unknown, filePath: string): void {
  const serialized = serialize(actual);
  const mode = resolveUpdateMode();
  const fileExists = fs.existsSync(filePath);

  if (!fileExists) {
    if (mode === &#39;all&#39; || mode === &#39;new&#39;) {
      const dir = path.dirname(filePath);
      if (!fs.existsSync(dir)) {
        fs.mkdirSync(dir, { recursive: true });
      }
      fs.writeFileSync(filePath, serialized, &#39;utf-8&#39;);

The filePath flows from expect(value).toMatchFileSnapshot(filePath) at index.ts:1033-1035 with no sanitization, no check that the path is within an expected directory, and no symlink resolution.

Proof of Concept

import { expect, setUpdateMode } from &#39;@asymmetric-effort/nogginlessdom&#39;;

setUpdateMode(&#39;all&#39;);

// Writes arbitrary content to any writable path
expect(&#39;malicious content&#39;).toMatchFileSnapshot(&#39;/tmp/exploit/payload.txt&#39;);

// Path traversal via relative components
expect(&#39;data&#39;).toMatchFileSnapshot(&#39;../../../tmp/evil.txt&#39;);

// In CI environments, could overwrite CI config
expect(&#39;injected step&#39;).toMatchFileSnapshot(&#39;/home/runner/.github/workflows/backdoor.yml&#39;);

Impact

In CI/CD environments where test files may come from untrusted pull requests, this allows writing to any writable filesystem location with directory creation. An attacker could overwrite configuration files, inject code into build artifacts, or modify CI pipeline definitions.

Fix

Fixed in commit https://github.com/asymmetric-effort/NogginLessDom/commit/785e6ac6e124d1a89b3ccf40bbd75fc8e4cb215d on main. The matchFileSnapshot function now validates that the resolved file path is within the project root directory (defaults to process.cwd(), configurable via optional projectRoot parameter). Paths that resolve outside the project directory are rejected with a descriptive error.

export function matchFileSnapshot(
  actual: unknown,
  filePath: string,
  projectRoot?: string,
): void {
  const root = projectRoot ?? process.cwd();
  const resolved = path.resolve(root, filePath);
  if (!resolved.startsWith(root + path.sep) &amp;&amp; resolved !== root) {
    throw new Error(
      `File snapshot path must be within the project directory: ${filePath}`,
    );
  }
  // ... all subsequent file I/O uses `resolved` instead of `filePath`
}

Which versions are affected by GHSA-322x-v876-g883?

2 open source packages ship an affected version, including @asymmetric-effort/nogginlessdom.

Package	Affected	Fixed in
`@asymmetric-effort/nogginlessdom` npm	All versions	`0.0.22`
`@asymmetric-effort/nogginlessdom` npm	All versions	`0.0.22`

How do I fix GHSA-322x-v876-g883?

Upgrade @asymmetric-effort/nogginlessdom to 0.0.22 or later.

Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.

Is GHSA-322x-v876-g883 being exploited?

There is no known exploitation of GHSA-322x-v876-g883 in the wild and no public exploit code.