# MAL-2026-12586: Malicious code in checkout-post-installment-client-agreement-accept-am (npm)


- **Type:** Malicious package
- **Package:** `checkout-post-installment-client-agreement-accept-am` (npm)
- **Published:** 5 Aug 2026

## What is MAL-2026-12586?

MAL-2026-12586 is a malicious package in checkout-post-installment-client-agreement-accept-am, published on 5 Aug 2026. 

### Official description

On require(), index.js loads _support.js which assembles Cloudflare Workers hostnames (oob-worker.cf100-416.workers.dev, oob-worker.cf102-baf.workers.dev, oob-worker.cf103-070.workers.dev) via array-join concealment and fetches a platform-specific binary over HTTPS, with a DNS-TXT base64-chunk fallback channel served from sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru and net.dl.wel1.ru. The retrieved bytes are written to a temp path with a disguised name (.cache_<rnd> on Unix, dotnet_diag_<rnd>.exe on Windows), chmod 0755'd, and detached-spawned via /bin/sh -c or cmd /c start, so the payload runs at import time with the installer's privileges. A second dropper implementation with the same fetch/write/chmod 755/spawn primitives is bundled in lib/telemetry.js under an 'Analytics SDK' cover story, using concatenated API names (chmod+Sync, child_+process) and base64 buffer decoding. Package name and 'telemetry/analytics' framing are cover-story labels; the actual behavior is remote code delivery and execution on the installer's host from author-controlled infrastructure.

## What should I do about MAL-2026-12586?

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-2026-12586 is a malicious package: checkout-post-installment-client-agreement-accept-am (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-2026-12586/ (Markdown: https://insights.sbomify.com/MAL-2026-12586/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12586

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-12586/
Summaries are generated and may contain mistakes; the official description above is the record.