Anthropic: Zhipu GLM-5.3 has end-to-end network utilization capabilities

On September 29, 2026, the Anthropic Frontier Red Team published a research article authored by Andrew Fasano, Marius Fleischer, Cole McFaul, Robert Xiao, and Tripp Gallagher. The article states that about five months ago, Anthropic released the Claude Mythos Preview through Project Glasswing in a limited manner, as it can autonomously construct end-to-end exploit capabilities; trusted defenders discovered over 10,000 vulnerabilities in critical software based on this, and similar capabilities have now spread to other models.

The article mentions that the GLM-5.3 developed by ZhiPu AI (known overseas as Z.ai) is similar to the Claude Mythos Preview, possessing strong autonomous end-to-end exploit development capabilities, but it is released with open weights and lacks meaningful abuse restrictions. In simulated tests, the success rate of bypassing GLM-5.3 defenses using simple methods was about 64% to 100%, while the same methods failed to make the protected Claude model perform harmful tasks; these capabilities can also be used by defenders to strengthen systems.

On September 17, 2026, the National Institute of Standards and Technology's Artificial Intelligence Standards and Innovation Center assessed that GLM-5.3 is currently the most powerful open-weight model in terms of network capabilities, lagging behind the U.S. frontier by about four months in its network benchmarks, and Anthropic stated that the capability conclusions are generally consistent.