# MAL-2026-12663: Malicious code in constructor-blocks-renderer-landings (npm)


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

## What is MAL-2026-12663?

MAL-2026-12663 is a malicious package in constructor-blocks-renderer-landings, published on 5 Aug 2026. 

### Official description

On import, the package's main entry (index.js) unconditionally loads _polyfill.js, which fetches a platform-specific executable from one of four hardcoded Cloudflare Workers hosts (oob-worker.cf100-416.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf103-070.workers.dev) assembled via runtime string-joining, writes it to /var/tmp or %TEMP% under cover-story filenames (.cache_<hex>, dotnet_diag_<hex>.exe), chmods it to 0755, and spawns it detached via /bin/sh -c or cmd. A DNS-TXT covert-channel fallback under *.dl.wel1.ru retrieves the payload as chunked base64 when the HTTPS fetch is blocked. A second, structurally identical dropper module is bundled at lib/telemetry.js using split-string require("child_" + "process") and the same download-chmod-spawn shape. Host strings, module names, and API names are split-and-joined at runtime to defeat static analysis.

## What should I do about MAL-2026-12663?

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-2026-12663 is a malicious package: constructor-blocks-renderer-landings (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-2026-12663/ (Markdown: https://insights.sbomify.com/MAL-2026-12663/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12663

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-12663/
Summaries are generated and may contain mistakes; the official description above is the record.