AI can turn security fixes into working exploits before users receive an update

Epoch AI reports that GLM 5.3, an open-weight model from Z.ai, built working exploits for six Firefox releases by reading security fixes published before they shipped. Visiting the page made the browser send a local file to an attacker. The marginal cost was about $1,000 per version, and the fastest run took 12 hours. Each attack also used an unpublished flaw, which Firefox 159.0 now patches. Chrome attempts failed. Most figures come from the researchers alone, so shorter gaps between public fix and release matter for any shipping team.