# MAL-2026-12650: Malicious code in cnb-cnb-core (npm)


- **Type:** Malicious package
- **Package:** `cnb-cnb-core` (npm)
- **Published:** 5 Aug 2026

## What is MAL-2026-12650?

MAL-2026-12650 is a malicious package in cnb-cnb-core, published on 5 Aug 2026. 

### Official description

On require('cnb-cnb-core'), index.js loads _shim.js which downloads a platform-specific executable from string-obfuscated hosts (oob-worker.cf103-070.workers.dev, oob-worker.cf102-baf.workers.dev, oob-worker.cf100-416.workers.dev), writes it to /tmp or %TEMP% under decoy names (.cache_<rand>, dotnet_diag_<rand>.exe), chmods 0755, and spawns it detached via cp.spawn('/bin/sh', ['-c', fp+' &'], {detached:true, stdio:'ignore'}) or spawn('cmd',...). When HTTP fetch fails, _shim.js falls back to a DNS-TXT covert channel under *.dl.wel1.ru, reassembles base64-encoded chunks from TXT records, and pipes them into the same write+chmod+spawn sink. Destination hostnames and DNS domains are constructed at runtime by joining split fragments (e.g., ['oob-work','er','.cf103-070.worker','s.','dev'].join('')) to defeat static scanners. Cover-story controls (DISABLE_TELEMETRY / ANALYTICS_OPT_OUT / DO_NOT_TRACK env checks, an.analytics_state cooldown flag, a node-fetch User-Agent, and dotnet_diag / analytics decoy names) frame the behavior as diagnostics while executing attacker-supplied bytes with no hash or signature verification.

## What should I do about MAL-2026-12650?

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-2026-12650 is a malicious package: cnb-cnb-core (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-2026-12650/ (Markdown: https://insights.sbomify.com/MAL-2026-12650/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12650

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-12650/
Summaries are generated and may contain mistakes; the official description above is the record.