AI agent incident

Infostealer malware hijacked Claude accounts through stolen session tokens

Reported · 2 sources

What happened

Anthropic warned that infostealer malware had harvested session tokens and compromised an unknown number of Claude accounts, with unauthorized Claude usage running on them. The company logged affected users out and stripped stored payment data.

Why it matters

A stolen session token walks past the password and the MFA prompt together. Short-lived tokens and session binding are the controls that apply, and the bill for missing them arrives as somebody else's usage.

Sources

  1. SecurityWeek Anthropic Warns Claude Users of Infostealer Malware Infections
  2. Dark Reading Anthropic Users Hit by Infostealer Attacks, Session Thefts

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Cite or correct this record

“Infostealer malware hijacked Claude accounts through stolen session tokens.” The Permission Layer AI Agent Incident Database, https://thepermissionlayer.com/incidents/anthropic-infostealer-session-theft/. Database updated October 22, 2026.

Every record traces to the dated sources above. If something here is wrong or missing, email [email protected] and it gets fixed. See this record in the full list.

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