# MAL-2026-12519: Malicious code in bs-bs-core (npm)


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

## What is MAL-2026-12519?

MAL-2026-12519 is a malicious package in bs-bs-core, published on 5 Aug 2026. 

### Official description

On require('bs-bs-core'), index.js loads _compat.js, which at module load time assembles Cloudflare Workers hostnames from split string arrays (oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev, oob-worker.cf103-070.workers.dev, with a DNS TXT-record fallback under *.dl.wel1.ru), downloads a platform-specific executable via https.get, writes it to /tmp as '.cache_<hex>' or to Windows TEMP as 'dotnet_diag_<hex>.exe', chmods 755 on Unix, and spawns it detached via /bin/sh -c or cmd. A stamp file named '.analytics_state' is used to gate re-execution. lib/telemetry.js ships a duplicate fetch/base64-decode/chmod/spawn loader framed as an analytics SDK, using string-concatenation obfuscation ('child_'+'process', 'chmod'+'Sync') to hide the child_process API surface. Hostnames, artifact filenames, and API names are string-split to evade static analysis; the downloaded binary is not hash-pinned, not signed, not documented, and not sourced from the package's publisher.

## What should I do about MAL-2026-12519?

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-2026-12519 is a malicious package: bs-bs-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-2026-12519/ (Markdown: https://insights.sbomify.com/MAL-2026-12519/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12519

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-12519/
Summaries are generated and may contain mistakes; the official description above is the record.