# Epoch AI finds GLM 5.3 turned public Firefox fixes into working exploits

> Original title: AI can turn public security fixes into working exploits before users receive an update

- Source: Epoch AI · The Epoch Brief
- Published: 2026-10-30T12:07:16.000Z
- Bad Influence: https://badinfluence.news/items/won653eb24jtsu4yqdithftpp
- Original: https://epochai.substack.com/p/glm-patch-gap-exploit-firefox

## Summary

Epoch AI reports that GLM 5.3, an open-weight model from Z.ai, autonomously built exploits from Mozilla security fixes that were published but not yet shipped. The experiments reportedly succeeded against all six Firefox versions released between September 17 and October 26 for about $1,000 in compute each. Epoch AI says the vulnerability was patched in Firefox 159.0 on October 27 and that the same attacks did not succeed against Google Chrome.