# MAL-2026-18361: Malicious code in mock-transactions-sdk (npm)


- **Type:** Malicious package
- **Package:** `mock-transactions-sdk` (npm)
- **Published:** 28 Oct 2026
- **Also known as:** GHSA-357r-x5jp-3p8f

## What is MAL-2026-18361?

MAL-2026-18361 is a malicious package in mock-transactions-sdk, published on 28 Oct 2026. 

### Official description

The package presents itself as a mock-transaction data generator but ships a dynamic-code loader. index.js builds the identifiers 'setTimeout', 'Function', 'Buffer', 'require', and 'process' by index-combining fragments of a string array and resolves the Function constructor indirectly through (function(){return this}).constructor.constructor. The documented getTransactions() entry point calls load_transaction_data(count), which concatenates the base64 `mark` fields from database.js, Caesar-shifts the result by count % 256, base64-decodes it, passes the decoded bytes to the reassembled Function constructor with Buffer, require, and process bound as arguments, and invokes the resulting function (deferred via setTimeout). package.json additionally declares python-shell, base-64, and axios as dependencies, none of which are referenced by the shipped source — these modules are reachable only through the require handle passed into the decoded payload, pre-provisioning an HTTP client and a Python subprocess runner for the executed blob. Any consumer that invokes the advertised getTransactions API therefore runs attacker-authored JavaScript on the installer's host with full Node capabilities, with the payload content controlled by the author through database.js. The identifier obfuscation, indirect Function-constructor resolution, Caesar+base64 payload encoding, and capability-pre-provisioned-but-unreferenced dependencies together are a deliberate loader, not instrumentation.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

## What should I do about MAL-2026-18361?

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-2026-18361 is a malicious package: mock-transactions-sdk (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-2026-18361/ (Markdown: https://insights.sbomify.com/MAL-2026-18361/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-18361

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-18361/
Summaries are generated and may contain mistakes; the official description above is the record.