UK Warns Open-Weight AI Cyber Models Are Closing the Gap With Frontier Systems

The UK’s National Cyber Security Centre and AI Security Institute warned that rapidly improving AI models are eroding defenders’ advantage in cyber operations, with open-weight systems becoming increasingly capable and harder to control through traditional safeguards. In a public AISI evaluation, GLM-5.2 was identified as the most cyber-capable open-weight model tested in June 2026, with performance on some narrow cyber tasks comparable to Opus 4.6 and GPT-5.3-Codex, while longer-horizon cyber range performance aligned more closely with Opus 4.5; DeepSeek V4-Pro generally trailed GLM-5.2.

AISI said leading open-weight models now lag the closed-model cyber frontier by roughly 4 to 7 months, an improvement from the 6 to 10 month gap it measured through much of 2025. The agencies said that narrowing gap is significant because open-weight releases weaken protections such as monitoring, access controls, and user bans, while tested safeguards on recent open models were often ineffective or easily bypassed. They also noted that open-weight models are materially cheaper than comparable closed systems, shortening the window for governments, vendors, and network defenders to prepare for broader access to advanced cyber capabilities.