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Claude Mythos Executes End-to-End Intrusion From Initial Access to Full Domain Compromise

Anthropic's Claude Mythos Preview, its most cyber-capable model, autonomously completed an end-to-end enterprise intrusion simulation in restricted-access testing.

Anthropic's April 2026 system card describes Claude Mythos Preview as the first model to solve a private cyber range end to end and finish a corporate-network attack simulation an expert would need 10+ hours to complete. It scored 100% pass@1 on a 35-challenge Cybench subset and 0.83 on CyberGym versus 0.67 for Claude Opus 4.6. The model is limited to vetted partners under Project Glasswing; it failed an OT cyber range and could not find novel exploits in a fully patched sandbox.

GBHackers · 8d agoModel release1

GPT-6 Astra Scores 100% on ExploitBench as OpenAI Blocks PoC Exploit Requests

OpenAI releases GPT-6 Astra, scoring 100% on ExploitBench, but restricts it to secure code review by blocking PoC exploit generation.

OpenAI officially unveiled GPT-6 Astra days after the model reached the "Critical" cybersecurity capability threshold under its Preparedness Framework. The model claims 100% on ExploitBench (versus 78.5% for GPT-5.6 Sol), 98% on FrontierMath Tier 4, and 99.9% on ARC-AGI-3, and demonstrated exploit development including on two zero-days disclosed between June and August 2026. The released version is limited to secure code review and patching and refuses proof-of-concept exploit requests, with less restrictive safeguards planned via OpenAI Daybreak. OpenAI also launched a $1 billion "Daybreak for Frontline Defenders" program for critical infrastructure sectors and a pilot with the US MS-ISAC for public sector and water system defenders.

The Hacker News · 12d agoModel release1

OpenAI Launches GPT-5.6-Cyber with Reduced Safeguards for Exploit Development

OpenAI released GPT-5.6-Cyber for vulnerability research and pentesting via Daybreak Red, completing 95% of advanced cyber task evaluations.

GPT-5.6-Cyber, built on GPT-5.6 Sol, targets zero-day discovery, exploit chain development and incident response with reduced refusals, scoring 95.0% on OpenAI's Advanced Cybersecurity Completion Rate versus 1.5% for GPT-5.6 Sol and 57.3% for GPT-5.5-Cyber. The model found CVE-2026-15903 (CVSS 8.8), an out-of-bounds read/write in Chrome's V8 JavaScript engine that Google patched in mid-July 2026. It is available to trusted partners including CrowdStrike, Palo Alto Networks and Cloudflare through the Daybreak Red access tier.

The Hacker News · Aug 11, 2026Model releaseCVE-2026-15903