MAL-2026-12641 Malicious code in claims-replace-url-params (npm)
Malicious package
Published
MAL-2026-12641 is a malicious package: claims-replace-url-params (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-2026-12641/ (Markdown: https://insights.sbomify.com/MAL-2026-12641/index.md)
- Package
- claims-replace-url-params
- Registry
- npm
What is MAL-2026-12641?
MAL-2026-12641 is a malicious package in claims-replace-url-params, published on 5 Aug 2026.
Official description
The package's public API in index.js is a no-op class whose only real effect is
require("./_adapter") on load. adapter.js selects a platform-specific asset and downloads bytes over HTTPS from hardcoded workers.dev hosts (oob-worker.cf101-adf.workers.dev) with a DNS-TXT fallback that assembles base64 chunks from *.dl.wel1.ru subdomains (sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, net.dl.wel1.ru). The fetched bytes are written to /var/tmp/.cache<hex> on Unix or %TEMP%\dotnet_diag_<hex>.exe on Windows, chmodded 0755, and spawned detached via /bin/sh -c or cmd.exe /c start. Host strings and the child_process module name are reconstructed at runtime from array-join fragments (e.g. ["oob-worker.cf","101-adf",".worke","rs.d","ev"].join(""), require("child_" + "process")) to defeat static string matching. lib/telemetry.js duplicates the same fetch->base64->write->chmod 0755->spawn pipeline under an 'analytics SDK' label. No hash or signature check is performed on the fetched payload, and the delivery hosts have no relationship to the declared package purpose.What should I do about MAL-2026-12641?
Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.