Anthropic
Disclosed Aug 31, 20263 weeks agoUnverified
Infostealer-stolen session cookies used to hijack Claude accounts
Anthropic emailed users and signed them out after finding their Claude login sessions had been stolen by infostealer malware such as Vidar, Lumma, StealC, RedLine, Acreed and Atomic Stealer; it removed saved payment methods and refunded unauthorized Claude charges.
What is known
| People affected | Not stated in the sources we have |
|---|---|
| Disclosed | Aug 31, 2026 |
| Attack | Hacking |
| Data exposed | Credentials and tokens, Payment cards, Prompts and chats |
| Sector | AI · US |
| Status | Unverified: not yet confirmed by an official notice, a filing or the organization |
Sources
| Source | |
|---|---|
| Anthropic locks out Claude users after infostealers hijack login sessionshelpnetsecurity.com · News | News |
Notices filed
| Where | Filed | People |
|---|---|---|
| Researchtotal | Aug 31 |
Other breaches at Anthropic
| Breach | Affected | ||||
|---|---|---|---|---|---|
| Shared Claude conversations appeared in Google search resultsJul 272 months agoExposed dataUnverified | Jul 272 months ago | Exposed data | AI | Unverified | Unknown |
| Claude Code source code accidentally published in npm packageMar 315 months agoExposed dataUnverified | Mar 315 months ago | Exposed data | AI | Unverified | Unknown |
| DeepSeek, Moonshot and MiniMax used 24,000 fraudulent accounts to distill ClaudeFeb 237 months agoAI or model | Feb 237 months ago | AI or model | AI | Confirmed | Unknown |
| Chinese state group manipulated Claude Code to attack about 30 organizationsNov 13, 202510 months agoHacking | Nov 13, 202510 months ago | Hacking | AI | Confirmed | Unknown |
| Cybercriminal used Claude Code to steal and extort data from at least 17 organizationsAug 27, 20251 year agoExtortion | Aug 27, 20251 year ago | Extortion | AI | Confirmed | Unknown |
| Contractor mistakenly emailed file of customer names and credit balances to third partyJan 29, 20242 years agoInsiderUnverified | Jan 29, 20242 years ago | Insider | AI | Unverified | Unknown |
History of this record
- 2026-09-25 · added · seed source
First seen 2026-09-25 (Research). Record counts are as reported. Not legal advice.