# MAL-2026-6848: Malicious code in log-format-thread (npm)


- **Type:** Malicious package
- **Package:** `log-format-thread` (npm)
- **Published:** 6 Jul 2026
- **Also known as:** GHSA-fw7h-6mmw-4jjr

## What is MAL-2026-6848?

MAL-2026-6848 is a malicious package in log-format-thread, published on 6 Jul 2026. 

### Official description

Package advertises itself as a log formatter but exposes an undocumented `threadContent` option on `createLogger()` that is forwarded to a worker thread which compiles and executes it via `new Function('require', payload)(require)` (src/worker.js lines 5-7, triggered from src/index.js lines 148-151). The eval only runs against a payload the caller explicitly supplies, so installing or requiring the package does not by itself execute attacker-controlled code, and there are no install hooks, no remote fetches, no credential reads, and no outbound exfiltration. However, the feature is undocumented in the README, is shaped like a backdoor primitive rather than logging functionality, and the package also pulls in `axios` and `request` despite the README claiming 'Zero dependencies'. Consumers who pass user-controlled or otherwise untrusted data into `threadContent` would expose their application to arbitrary code execution. Routing to human review so a maintainer can decide whether to publish a public advisory about the undocumented eval surface and the dependency mismatch.

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-2026-6848?

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-2026-6848 is a malicious package: log-format-thread (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-2026-6848/ (Markdown: https://insights.sbomify.com/MAL-2026-6848/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-6848

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-6848/
Summaries are generated and may contain mistakes; the official description above is the record.