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GPT-5.5 and Mythos Execute 32-Step Network Intrusion

GPT-5.5 and Mythos Execute 32-Step Network Intrusion

ATLAS OWASP HIGH Significant risk · Prioritise patching ▲ 7.5 Ars Technica Security

The UK's AI Security Institute (AISI) found that OpenAI's GPT-5.5 matches Anthropic's Mythos Preview on cybersecurity benchmarks, including a 32-step simulated corporate network intrusion. Both models successfully completed the 'The Last Ones' data-extraction simulation — a first for any AI system — suggesting autonomous offensive cyber capability is a general frontier-model property, not a one-vendor breakthrough. The findings raise urgent questions about responsible release practices and the pace at which LLMs can independently execute multi-stage attacks.

GPT-5.5 Matches Claude Mythos in Vulnerability Discovery

GPT-5.5 Matches Claude Mythos in Vulnerability Discovery

ATLAS OWASP HIGH Significant risk · Prioritise patching ▲ 7.2 Simon Willison

The UK's AI Security Institute has evaluated OpenAI's GPT-5.5 for offensive cybersecurity capabilities, finding it comparable to Anthropic's Claude Mythos model in identifying security vulnerabilities. Unlike Mythos, GPT-5.5 is generally available, meaning its vulnerability-discovery capabilities are accessible to a broad population including malicious actors. This raises significant concerns about the proliferation of AI-assisted exploitation tools at scale.

Zealot: Autonomous LLM Cloud Penetration Testing System

Zealot: Autonomous LLM Cloud Penetration Testing System

ATLAS OWASP CRITICAL Active exploitation · Immediate action required ▲ 9.0 Palo Alto Unit 42

Unit 42 researchers built 'Zealot,' a multi-agent LLM-powered penetration testing system capable of autonomously executing end-to-end offensive operations against cloud infrastructure, demonstrating that AI acts as a significant force multiplier for cloud attacks. The system successfully attacked a misconfigured GCP sandbox environment using a supervisor-coordinated architecture of specialist agents, validating that agentic AI can operate at machine speed against real cloud misconfigurations. This research follows Anthropic's November 2025 disclosure of a state-sponsored AI-orchestrated espionage campaign and marks a critical inflection point in understanding autonomous AI offensive capabilities.

Qihoo 360 AI System Discovers 1,000 Vulnerabilities

Qihoo 360 AI System Discovers 1,000 Vulnerabilities

ATLAS OWASP HIGH Significant risk · Prioritise patching ▲ 8.2 SecurityWeek

Chinese cybersecurity firm 360 Digital Security Group claims its multi-agent AI system autonomously discovered nearly 1,000 vulnerabilities, including a critical Office zero-day allegedly dormant for eight years, drawing direct comparisons to Anthropic's restricted Claude Mythos model. The developments signal that AI-driven autonomous vulnerability discovery is rapidly proliferating beyond tightly controlled Western research environments. This raises significant concerns about AI-accelerated offensive capabilities reaching nation-state threat actors at scale.

Autonomous Exploit Generation: Claude Mythos Risk

Autonomous Exploit Generation: Claude Mythos Risk

ATLAS OWASP HIGH Significant risk · Prioritise patching ▲ 8.5 Schneier on Security

Bruce Schneier analyses Anthropic's Claude Mythos Preview and Project Glasswing, a controlled deployment programme aimed at finding and patching software vulnerabilities before the model is publicly released due to its advanced cyberattack capabilities. The piece highlights a growing offensive AI capability gap, noting that newer LLMs can autonomously chain memory corruption bugs and operationalise exploits without human orchestration, while observing that defenders currently retain a marginal advantage because vulnerability discovery is easier than exploitation. Schneier warns that this advantage is narrowing rapidly and that the industry must prepare for a world of commoditised zero-day exploits.

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LLM Jailbreak Adoption Surges Across 160+ Cybercrime Forums

ATLAS OWASP MEDIUM Moderate risk · Monitor closely ▲ 6.2 Schneier on Security

A new academic paper analysed over 160 cybercrime forum conversations to understand how threat actors are discussing and adopting AI tools for criminal purposes. The research documents both misuse of legitimate AI platforms and attempts to build bespoke criminal AI models, revealing early-stage diffusion of AI capabilities within cybercriminal communities. The findings carry practical implications for law enforcement and security practitioners monitoring the evolving AI-enabled threat landscape.

US summons bank bosses over cyber risks from Anthropic's latest AI model

US summons bank bosses over cyber risks from Anthropic's latest AI model

ATLAS OWASP CRITICAL Active exploitation · Immediate action required ▲ 8.5 HN AI Security

The US Treasury convened major bank executives to discuss cybersecurity risks posed by Anthropic's unreleased Claude Mythos model, which the company claims has surpassed nearly all human experts at finding and exploiting software vulnerabilities. A code leak prompted Anthropic to publicly acknowledge the model's unprecedented offensive cyber capability, raising systemic financial sector risk concerns. The meeting signals growing regulatory awareness of AI-enabled cyber threats to critical financial infrastructure.

Anthropic Mythos AI Autonomously Discovers Zero-Day Exploits

Anthropic Mythos AI Autonomously Discovers Zero-Day Exploits

ATLAS OWASP HIGH Significant risk · Prioritise patching ▲ 8.2 Dark Reading

Anthropic has released a preview of 'Mythos,' an AI model reportedly capable of autonomously discovering and exploiting critical zero-day vulnerabilities, raising significant dual-use concerns. While Anthropic claims the model ships with access controls, the security community is scrutinising whether those safeguards are sufficient to prevent misuse by malicious actors. The development represents a pivotal moment in the arms race between offensive AI capabilities and defensive governance frameworks.

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