GoKawiilGLM 5.3 open-weight model shown exploiting Firefox patch gap, researchers say
Researchers report that GLM 5.3, an open-weight AI model released by Z.ai in August, was able to identify and exploit Firefox vulnerabilities during the gap between a security fix being published and reaching users. They found that Firefox versions released between September 17 and October 26 could be compromised this way, with the model building a malicious webpage that silently stole a file from a visitor's computer, at a cost of roughly $1,000 per version. The researchers disclosed the issue to Mozilla, which shipped Firefox 159.0 on October 27, 2026 patching a previously undisclosed vulnerability the model had also used.