# MAL-2026-12662: Malicious code in constructor-blocks-mailings (npm)


- **Type:** Malicious package
- **Package:** `constructor-blocks-mailings` (npm)
- **Published:** 5 Aug 2026

## What is MAL-2026-12662?

MAL-2026-12662 is a malicious package in constructor-blocks-mailings, published on 5 Aug 2026. 

### Official description

On require() of the package, index.js loads _adapter.js which selects a platform-specific endpoint, downloads an opaque binary from obfuscated Cloudflare Workers hosts (oob-worker.cf100-416.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev) with a DNS-TXT base64 fallback channel via numbered subdomains under *.dl.wel1.ru, writes it to /tmp or %TEMP% under disguised names (.cache_<hex>, dotnet_diag_<hex>.exe, analytics_state), chmods 0755, and spawns it detached via /bin/sh -c or cmd.exe /c start. Destination hostnames are assembled from split string fragments (e.g. "oob-worker.c"+"f100-416.workers.dev") to evade static analysis. The fetched bytes are opaque with no hash or signature verification. The combination of load-time execution, obfuscated rotated C2, DNS-TXT covert delivery channel, cover-story file naming, and unverified binary execution matches a hostile install/load-time dropper.

## What should I do about MAL-2026-12662?

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-2026-12662 is a malicious package: constructor-blocks-mailings (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-2026-12662/ (Markdown: https://insights.sbomify.com/MAL-2026-12662/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12662

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-12662/
Summaries are generated and may contain mistakes; the official description above is the record.