AI roundup
Anthropic Expands Claude Mythos 5 Access for Cyber Defense
Sat 22 August 2026
What Shipped
Anthropic is expanding Claude Mythos 5 availability beyond the initial Project Glasswing cohort of approximately 100 US partners to Enterprise customers via Claude Security. The integration allows codebase scanning for vulnerabilities and patch suggestion workflows using the full model capabilities. Anthropic is also embedding Mythos 5 into third-party security tools and launching the $35 million Defender Advantage Fund (0xDAF) to credit open-source vulnerability patching and security automation research. Access remains contingent on the Cyber Verification Program, with plans for broader expansion.
Pricing and Architecture
Pricing is set at $10 per million input tokens and $50 per million output tokens, a 60% reduction from Mythos Preview’s $25/$125 rate. The model supports a 1 million token context window and operates without a safety fallback classifier, unlike the Fable 5 variant. Anthropic has not disclosed parameter counts. All usage carries 30-day mandatory data retention for safety monitoring.
Cybersecurity Benchmarks
On ExploitBench, Mythos 5 scores 78%. Against 147 Firefox vulnerabilities, it achieves arbitrary code execution in 88.4% of trials, compared to Preview’s 70.8% and Opus 4.8’s 8.8%. The model reproduces target vulnerabilities in CyberGym on 83.8% of single attempts and generates any crash in 99.4% of cases. On OSS-Fuzz, it reaches memory-safety crashes or better on 80.0% of targets and achieves write primitives on 32.4%.
Competitive Positioning
Mythos 5 outperforms Opus 4.8 and GPT-5.5 on defensive coding and exploit-generation tasks. SWE-bench Pro scores hit 80.3% versus Opus 4.8’s 69.2% and GPT-5.5’s 58.6%. On AutoNudge, Mythos 5 achieves 78% capability compared to GPT-5.5’s 34% and Opus 4.8’s 40%. The UK AI Security Institute found it capable of attacking small enterprise networks with weak security where initial access was already obtained, though it made only limited progress on the “Cooling Tower” industrial control system test.
Source: Anthropic (community mirror)