# MAL-2026-5727: Malicious code in vite-config-optimizer (npm)


- **Type:** Malicious package
- **Package:** `vite-config-optimizer` (npm)
- **Published:** 13 Jun 2026
- **Also known as:** GHSA-5rwj-cgwr-q954

## What is MAL-2026-5727?

MAL-2026-5727 is a malicious package in vite-config-optimizer, published on 13 Jun 2026. 

### Official description

package.json declares a postinstall hook `node -e "require('./loader.js')"` that auto-executes on every `npm install`. loader.js spawns a detached child Node process running a dropper that hex-decodes a hidden URL (`https://jsonkeeper.com/b/L435A`, an anonymous, mutable JSON paste host), HTTPS-GETs the response body, writes it to a temp file under `/tmp/wpc-*/cfg-*.js`, and `require()`s it — running arbitrary attacker-controlled JavaScript inside the installer's Node process with the installer's privileges. The remote endpoint is concealed as a hex literal decoded with `Buffer.from(..., 'hex').toString()` to evade plain-text URL scanners, and the dropper is detached and unref'd to hide its activity. The package's advertised identity is also a cover story: the name and description claim it is a Vite configuration plugin, but the declared repository points at `webpack-tools/webpack-cache-plugin`, the main module exports a `WebpackCachePlugin` class, and the only install-time behavior is the dropper. Anyone running `npm install vite-config-optimizer` (directly or transitively) executes whatever bytes the paste host serves at request time.

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-2026-5727?

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-2026-5727 is a malicious package: vite-config-optimizer (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-2026-5727/ (Markdown: https://insights.sbomify.com/MAL-2026-5727/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-5727

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-5727/
Summaries are generated and may contain mistakes; the official description above is the record.