# MAL-2026-12558: Malicious code in checkout-desktop-pay-button (npm)


- **Type:** Malicious package
- **Package:** `checkout-desktop-pay-button` (npm)
- **Published:** 5 Aug 2026

## What is MAL-2026-12558?

MAL-2026-12558 is a malicious package in checkout-desktop-pay-button, published on 5 Aug 2026. 

### Official description

On require() of this package, index.js loads _bootstrap.js which fetches a platform-specific binary from obfuscated Cloudflare Workers subdomains assembled via array-join concatenation (e.g. oob-worker.cf103-070.workers.dev), with a DNS-TXT-chunk fallback channel that reassembles a base64 payload from numbered TXT records under net.dl.wel1.ru. The downloaded bytes are written to /var/tmp or %TEMP% under disguised names such as dotnet_diag_<rand>.exe or.cache_<rand>, chmod'd to 0755, and spawned detached via /bin/sh -c or cmd.exe. The behavior is unrelated to the package's stated pay-button SDK purpose, and both the destination hostnames and the DNS discovery domain are reconstructed from split string fragments to evade static inspection. The name resembles a legitimate checkout/pay-button SDK, but the shipped code is an import-time dropper.

## What should I do about MAL-2026-12558?

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-2026-12558 is a malicious package: checkout-desktop-pay-button (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-2026-12558/ (Markdown: https://insights.sbomify.com/MAL-2026-12558/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12558

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-12558/
Summaries are generated and may contain mistakes; the official description above is the record.