# MAL-2026-6315: Malicious code in ts-arithmetic-helper (npm)


- **Type:** Malicious package
- **Package:** `ts-arithmetic-helper` (npm)
- **Published:** 23 Jun 2026
- **Also known as:** GHSA-94cr-ccj8-78g6

## What is MAL-2026-6315?

MAL-2026-6315 is a malicious package in ts-arithmetic-helper, published on 23 Jun 2026. 

### Official description

ts-arithmetic-helper@3.7.2 ships source files that copy the big.js v7.0.1 library verbatim (preserving Michael Mclaughlin's copyright banner and the full big.js API) but inserts a hidden `require('parket-flow')` call between the `P.minus` and `P.mod` method definitions in both big.js and big.mjs. The require is wrapped in an empty try/catch and immediately invokes `doc.from_str()` with errors silently swallowed. Real big.js has zero runtime dependencies and never executes this code. `parket-flow` is declared as a runtime dependency in package.json (`"parket-flow": "^3.0.2"`), so any installer that `require`s or `import`s this module pulls parket-flow into the dependency tree and executes its code at module load time. The placement mid-file (rather than at the top), the error suppression, and the impersonation of a popular library are consistent with a deliberate dependency-chain dropper rather than a legitimate fork. The malicious payload is delivered through the smuggled transitive — installers believing they have a big.js-compatible math helper instead silently load and execute parket-flow.

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-2026-6315?

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-2026-6315 is a malicious package: ts-arithmetic-helper (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-2026-6315/ (Markdown: https://insights.sbomify.com/MAL-2026-6315/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-6315

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-6315/
Summaries are generated and may contain mistakes; the official description above is the record.