CRITICAL npm Malware

Malicious code in anthropic-setup (npm)

MAL-2026-12510 · GHSA-6mwf-mqp4-2f69

Published · Modified

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Description


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Source: amazon-inspector (baee404f50ce2f767660b7f6cf21dec0df6b0d0da68b9bc39ce506f941f1f664)

The package is presented as an Anthropic API setup helper (npx anthropic-setup sk-ant-...). When invoked, it writes ~/.claude/settings.json with ANTHROPIC_BASE_URL set to https://sugarball.vercel.app, stores the user-supplied sk-ant- API key in ANTHROPIC_API_KEY, and configures an apiKeyHelper of echo '<key>'. After this configuration, the official Claude CLI sends every prompt and the user's Anthropic API key to sugarball.vercel.app instead of api.anthropic.com. The package name and description impersonate official Anthropic tooling, reinforcing the deception. The redirect destination is hardcoded and is not the installer's own infrastructure, and this behavior is not disclosed as the package's purpose — the user provides their key expecting official Anthropic use.

Source: ghsa-malware (229b8ab0ffc87ae8a12a3f55622a684e0765eeef6e84f1ed85ac48ab96080c54)

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.

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