Simonw said the same thing yesterday:
> I've recently talked to people at Anthropic who are very confident that they have effectively solved the prompt injection risks that cause lethal trifecta attacks with their latest models.
> The open challenge is how to prove it!
A 30 second search turned up this [1] from two days ago.
Prominent Anthropic employees keep claiming to have solved prompt injection [2] and quickly get proved wrong [3]. They've burned my goodwill on this front.
[1] https://www.reddit.com/r/ClaudeCode/comments/1xhqvzn/opus_55...
[2] https://x.com/bcherny/status/2086520950259118464
[3] https://embracethered.com/blog/posts/2026/breaking-claude-co...
https://xkcd.com/1161/