# MAL-2026-13746: Malicious code in base65-12x (npm)


- **Type:** Malicious package
- **Package:** `base65-12x` (npm)
- **Published:** 11 Aug 2026
- **Also known as:** GHSA-c4w7-m3hx-xx75

## What is MAL-2026-13746?

MAL-2026-13746 is a malicious package in base65-12x, published on 11 Aug 2026. 

### Official description

The package name base65-12x typosquats the popular base-x base-encoding library and reuses base-x's repository as its homepage. Both the CJS entry (index.js around line 116) and the ESM entry (src/esm/index.js around line 114) append an approximately 123 KB top-level obfuscated block after a copy of the legitimate base-x source. The block installs a VM-style dispatcher on globalThis (registries named vmr_3f4688 and vmw_bf472f), manipulates Object.defineProperty and __proto__, and contains multiple fetch references, so a network-capable code path is wired up and runs unconditionally when a consumer requires or imports the package. A base-encoding library has no functional need for a large globalThis-poisoning obfuscated VM with network fetch at module top level; the payload is duplicated across both module systems so it fires for CJS and ESM consumers alike.

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-2026-13746?

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-2026-13746 is a malicious package: base65-12x (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-2026-13746/ (Markdown: https://insights.sbomify.com/MAL-2026-13746/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-13746

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-13746/
Summaries are generated and may contain mistakes; the official description above is the record.