the only one that was publicly admitted to and which you happened to have read about.
even prior to ai, most companies and organizations would never admit to being breached unless irrefutable proof of the breach came to light. in other cases it is just immediately classified and the public finds out 20 years later (or, depending on the country, simply covered up).
"A model being tested broke out of its sandboxing and hacked a production system of a different organisation using a previously-unknown vulnerability, in order to steal test results, and that proves anthropic were worried for no reason months ago about future models being security issues" ...?
Anthropic have released a lot of security patches in recent months, so many that many open source maintainers are facing burnout (google it). It's public knowledge that they weren't lying, you can look at the code. Their ridiculous guardrails were so that projects could patch and prepare for more models like this one coming out.