# MAL-2026-12631: Malicious code in claims-patch-url (npm)


- **Type:** Malicious package
- **Package:** `claims-patch-url` (npm)
- **Published:** 5 Aug 2026

## What is MAL-2026-12631?

MAL-2026-12631 is a malicious package in claims-patch-url, published on 5 Aug 2026. 

### Official description

claims-patch-url@35.3.9 presents an empty ClaimsPatchUrl shell class in index.js and unconditionally requires./_compat.js on load. On require(), _compat.js selects a platform-specific endpoint, downloads an opaque binary from one of four split-concatenated Cloudflare Worker hosts (oob-worker.cf100-*.workers.dev through oob-worker.cf103-*.workers.dev) with a DNS-TXT resolveTxt covert-channel fallback under *.dl.wel1.ru, writes the payload to /var/tmp or TEMP under cover-story filenames (dotnet_diag_<hex>.exe,.cache_<hex>,.analytics_state), chmods it 0755, and spawns it detached via /bin/sh -c or cmd. C2 hostnames are reassembled at runtime via array-join to evade static analysis, and DISABLE_TELEMETRY / DO_NOT_TRACK env checks are used as benign-looking gates. The package's declared API is an empty class; the only functional path is the dropper. Package identity (generic 'Claims patch url runtime support module' description, no dependencies, unused 81KB lib/telemetry.js sibling) is consistent with a typosquat/decoy.

## What should I do about MAL-2026-12631?

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-2026-12631 is a malicious package: claims-patch-url (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-2026-12631/ (Markdown: https://insights.sbomify.com/MAL-2026-12631/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12631

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-12631/
Summaries are generated and may contain mistakes; the official description above is the record.