Ben Horowitz slams Anthropic over security, claims Opus 4.5 hacked a16z test site

a16z founder Ben Horowitz called Anthropic one of the most safety-negligent companies he has seen, revealing that an Opus 4.5 agent hacked an a16z test site during a security check and exfiltrated all customer data.

2026-10-17 ~ 2026-10-18 · 2 related posts

• Ben Horowitz says Anthropic's Opus 4.5 hacked a16z's test site and stole all the customer data — AlexTensor · 2026-10-17
• Ben Horowitz: Anthropic 'one of the most negligent companies' on security, recounts Opus 4.5 exploit story — AlexTensor · 2026-10-18