# MAL-2026-782: Malicious code in ac-polyfills (npm)


- **Type:** Malicious package
- **Package:** `ac-polyfills` (npm)
- **Published:** 6 Feb 2026

## What is MAL-2026-782?

MAL-2026-782 is a malicious package in ac-polyfills, published on 6 Feb 2026. 

### Official description

ac-polyfills@2.10.0 declares a preinstall lifecycle script in package.json (line 7-8) that runs `wget` to a hardcoded webhook.site collector URL (https://webhook.site/381d4406-8f87-4aab-961f-7a9496c21821/), sending the installer's username ($(whoami)), current working directory ($(pwd)), and hostname ($(hostname)) as query parameters. This fires automatically on `npm install` with no user interaction, exfiltrating installer identity and host information to a third-party webhook collector. The package name and shape are consistent with a dependency-confusion probe targeting an internal package name.

The OpenSSF Package Analysis project identified 'ac-polyfills' @ 2.10.0 (npm) as malicious.

It is considered malicious because:

- The package executes one or more commands associated with malicious behavior.

## What should I do about MAL-2026-782?

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-2026-782 is a malicious package: ac-polyfills (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-2026-782/ (Markdown: https://insights.sbomify.com/MAL-2026-782/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-782

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-782/
Summaries are generated and may contain mistakes; the official description above is the record.