claude-internal-utils (npm) · Malicious Code
Affects claude-internal-utilsSource GCVE Database
Malicious package : remove claude-internal-utils and rotate any secrets on hosts that installed it.
Data as of 8 Sep 2026, 09:23 UTC
Malicious package
Published to npm · OSV MAL-2026-4525
What to do
Remove claude-internal-utils from every project, lockfile and image that pulls it in. Treat any host that installed it as compromised: rotate the credentials, tokens and keys it could read, from a clean machine.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| npmclaude-internal-utils | Affected
| Fixed in– |
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Description
The npm package 'claude-internal-utils' version 9.0.5 is a malicious package impersonating an internal Anthropic namespace. It contains no legitimate library code but executes a postinstall script that collects system and environment information, including the installer's public IP, hostname, current working directory, and environment variables. This data is exfiltrated to a hardcoded attacker-controlled domain. The malicious code runs automatically during 'npm install' before any consumer code executes.