Open-weight AI models can exploit the patch gap

Researchers found that GLM 5.3, a widely available open-weight model released by Z.ai in August, could autonomously build exploits against all six Firefox releases between September 17 and October 26 using only information available at each version's release, at a marginal cost of about $1,000 per version. Visiting the model-built webpage caused the browser to read a local file and send it to an attacker's server without further user interaction, and the attacks also relied on an unpublished vulnerability that Mozilla has since patched in Firefox 159.0 (released October 27, 2026). Similar attacks on Google Chrome did not succeed as of writing, and the authors expect the threat to worsen as open-weight cyber capabilities improve.