# MAL-2026-5604: Malicious code in cache-section-helper (npm)


- **Type:** Malicious package
- **Package:** `cache-section-helper` (npm)
- **Published:** 11 Jun 2026
- **Also known as:** GHSA-wg39-m2jm-wxhp

## What is MAL-2026-5604?

MAL-2026-5604 is a malicious package in cache-section-helper, published on 11 Jun 2026. 

### Official description

package.json declares a postinstall hook (`node -e "require('./loader.js')"`) that runs automatically on every `npm install`. loader.js hex-decodes the string `68747470733a2f2f6a736f6e6b65657065722e636f6d2f622f4c34333541` to the URL `https://jsonkeeper.com/b/L435A`, fetches a JSON document from that anonymous paste host, extracts a `manifest.session` field, writes it to a temporary file under `os.tmpdir()/wpc-*/cfg-<ts>.js`, `require()`s it to execute the attacker-supplied JavaScript, then deletes the file to hide traces. The dropper is launched via `spawn(process.execPath, [tmpFile], { detached: true, stdio: 'ignore', cwd: os.tmpdir() }).unref()` so the child Node process outlives the npm install and runs without producing visible output. The package presents itself as a webpack caching helper (class `WebpackCachePlugin` in index.js, a README that instructs `npm install cache-helper` — a different name suggesting impersonation), but the advertised plugin code is trivial; the real behavior is the install-time dropper. Every installer fetches and executes attacker-controlled, mutable, unauthenticated code from a paste host with no integrity verification.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

## What should I do about MAL-2026-5604?

Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.

## Fix prompt for AI coding agents

```text
MAL-2026-5604 is a malicious package: cache-section-helper (npm). Every version was published to cause harm.

Task:
1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.
2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.
3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.
4. If the package is not used anywhere, say so and change nothing.

Reference: https://insights.sbomify.com/MAL-2026-5604/ (Markdown: https://insights.sbomify.com/MAL-2026-5604/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-5604

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-5604/
Summaries are generated and may contain mistakes; the official description above is the record.