# MAL-2026-5538: Malicious code in hex-type (npm)


- **Type:** Malicious package
- **Package:** `hex-type` (npm)
- **Published:** 11 Jun 2026
- **Also known as:** GHSA-jc42-pxfc-29x3

## What is MAL-2026-5538?

MAL-2026-5538 is a malicious package in hex-type, published on 11 Jun 2026. 

### Official description

Package metadata (description "A universally-unique, lexicographically-sortable, identifier generator", homepage github.com/ulid/javascript, build script `--name ulidx`, reused ULID source) impersonates the legitimate `ulid`/`ulidx` libraries, but the package adds a malicious dropper not present in those projects. `package.json` declares `"postinstall": "node dist/utils.js"`. On `npm install`, dist/utils.js re-spawns itself detached with `--bg`, copies dist/payload.js (~950KB) to a hidden directory named `MicrosoftSystem64` under LOCALAPPDATA / Application Support / ~/.local/share (impersonating a Windows system component), and registers OS-level persistence: a Windows Scheduled Task plus Run-key launching `wscript.exe` of a generated VBS, a Linux systemd --user service with `loginctl enable-linger`, or a `.config/autostart` fallback, and a detached spawn on macOS. The dropped payload.js bundles the `ws` WebSocket client/server, `pino` logging, `zod`, and references `https://huggingface.co/api` and `https://huggingface.co` — the building blocks of a long-running remote-controlled agent, with zero relation to ULID generation. Both the postinstall (`if (cpus.length <= 4...) return;`) and the agent (`MIN_CPU_COUNT = 5`) abort on hosts with ≤4 CPUs to evade sandboxes and low-core CI runners. This is unambiguous installer-side RCE plus persistence plus C2.

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-2026-5538?

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-2026-5538 is a malicious package: hex-type (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-2026-5538/ (Markdown: https://insights.sbomify.com/MAL-2026-5538/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-5538

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-5538/
Summaries are generated and may contain mistakes; the official description above is the record.