In late March 2026open on a new tab, Anthropic inadvertently released the internal Claude Code source material as part of an npm package that included a large internal source map file. Although the incident stemmed from a simple packaging mistake, threat actors were quick to capitalize on the resulting attention. Only 24 hours after the leak, they were able to create fake GitHub repositories to distribute credential-stealing malware disguised as “leaked” Claude Code downloads.
This incident demonstrates that security compromise is not limited to software vulnerabilities: human factors and organizational control gaps often serve as catalyst for threats and are primary drivers of material impact. In this blog entry, we will talk about our analysis of the threats capitalizing on this incident, the downstream risks of the leaked source code, and the actions organizations should take next.
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Source: Trend Micro
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