Anthropic releases Claude Sonnet 5.5 with the cyber limits it reserved for its best models

Anthropic has released Claude Sonnet 5.5, which scores 70.6% on the Terminal-Bench 4.0 agentic coding test against 10.3% for Sonnet 5 and 66.4% for the more expensive Opus 5.5. It is the first Sonnet to ship with frontier-style cyber safeguards and with classifiers that block reasoning extraction. Anthropic has released Claude Sonnet 5.5, which it ...

• Published date: 28-09-2026 06:30 PM