Anthropic Claude Opus 4.5 vs Anthropic Claude 3.5 Sonnet v2
Detailed comparison for LLMs
On Guardion's LLM vulnerability Benchmark, Anthropic Claude Opus 4.5 is the more secure of the two: Claude Opus 4.5 scores 3.4% and Claude 3.5 Sonnet v2 scores 4.4% on attack success rate (ASR) (lower is better). One or both scores are estimated from public safety evaluations pending a Guardion benchmark run.
Head-to-Head Overview
Claude Opus 4.5 is the overall winner in this comparison!
Attack Success Rate (lower is safer)
ASR for Anthropic Claude Opus 4.5 vs Anthropic Claude 3.5 Sonnet v2. Green marks the safer model on each metric. Only the overall score is available for estimated models.
Overall (ASR)
TAP Attack Method (ASR)
Crescendo Attack Method (ASR)
Zero-Shot (ASR)
Key Highlights
- Anthropic Claude Opus 4.5 has a lower Overall (ASR).
- Anthropic Claude 3.5 Sonnet v2 has a lower TAP Attack Method (ASR).
- Anthropic Claude 3.5 Sonnet v2 has a lower Crescendo Attack Method (ASR).
- Anthropic Claude 3.5 Sonnet v2 has a lower Zero-Shot (ASR).
Security Profile
Outward is better on every axis.
Frequently asked questions
Is Anthropic Claude Opus 4.5 or Anthropic Claude 3.5 Sonnet v2 more secure?
On Guardion's LLM vulnerability Benchmark, Anthropic Claude Opus 4.5 is the more secure of the two: Claude Opus 4.5 scores 3.4% and Claude 3.5 Sonnet v2 scores 4.4% on attack success rate (ASR) (lower is better). One or both scores are estimated from public safety evaluations pending a Guardion benchmark run.
What is the attack success rate (ASR) of Claude Opus 4.5 vs Claude 3.5 Sonnet v2?
Claude Opus 4.5 has a 3.4% ASR and Claude 3.5 Sonnet v2 has a 4.4% ASR — the share of adversarial prompts that succeed across zero-shot, TAP, and Crescendo attacks. Lower is safer.
How were Claude Opus 4.5 and Claude 3.5 Sonnet v2 tested?
Both were red-teamed with the HarmBench framework across zero-shot, TAP (Tree of Attacks with Pruning), and Crescendo multi-turn attacks, scored by Attack Success Rate.