Epoch AI: GLM 5.3 autonomously builds Firefox exploit chain
What happened
On 30 October 2026, The Decoder reported that Epoch AI researchers found the open-weight model GLM 5.3 can autonomously build a complete Firefox exploit chain within 48 hours with zero human input. The model exploited the gap between the release of security patches and users updating, attacking six Firefox versions released between 17 September and 26 October, at an API cost of about $1,000 per successful attack. The information disclosed so far centres on Epoch AI's finding, with no reports of vendor response or follow-up remediation.
Written by AI from the reports · updated 2 h ago
Timeline
Follow the reports to see the event from each side.
- The DecoderSelectedOpen-weight model GLM 5.3 built full Firefox exploit chains with zero human input in under 48 hours
Epoch AI researchers say the widely available AI model GLM 5.3 turned public security fixes into working exploits before updates reached Firefox users. It autonomously compromised six Firefox releases for about $1,000 in API fees each without triggering safeguards from any provider tested.
Heat of this event
Not enough continuous observations yet to draw a trend.