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Cybersecurity

Claude Code source leaks; 140 fake repos seed Vidar within hours

On April 4 an Anthropic engineer accidentally pushed an internal branch of Claude Code to a public GitHub fork, exposing source for ~3 hours before takedown. Within hours, threat actors seeded ~140 fake 'claude-code' and 'claude-cli' GitHub repositories using the leaked code as bait, bundling the Vidar infostealer in post-install npm hooks. Checkmarx tracked at least 1,200 malicious installs before GitHub's trust & safety team removed the repos. A textbook case of supply-chain opportunism on fresh leaked code.

Supply ChainAnthropicVidarGitHubCheckmarx

Why it matters

Live demonstration that every major AI-coding-tool release now has a ~hours-window supply-chain attack surface. The ~140 weaponized repos and ~1,200 infected installs within one workday set the new baseline for how fast adversaries turn leaks into RATs. Every company deploying AI dev tools needs npm/PyPI provenance checks and internal mirror enforcement, today — not next quarter.

Impact scorecard

8.3/10
Stakes
8.5
Novelty
7.5
Authority
8.5
Coverage
8.0
Concreteness
9.0
Social
8.5
FUD risk
1.5
Coverage28 outlets · 5 tier-1
The Hacker News, BleepingComputer, Ars Technica, The Register, Dark Reading, SecurityWeek, …
X / Twitter6,800 mentions
@checkmarx · 4,100 likes
@GossiTheDog · 8,900 likes
Reddit2,200 upvotes
r/netsec
r/netsec, r/cybersecurity, r/programming

Trust check

high

Multi-source corroboration: Anthropic incident timeline, Checkmarx IoC list, GitHub trust & safety takedown log, and independent npm-registry analysis. Concrete numbers, CVE-less but attacker infra documented.

Primary source ↗