Epoch AI published research on October 29, 2026, reporting that GLM 5.3, an open-weight model released by Z.ai in August 2026, can exploit the browser patch gap — the window between a security fix becoming public and reaching users — to compromise six recent Mozilla Firefox releases at a marginal cost of about $1,000 per version. Epoch said the model operated autonomously and repeatedly rediscovered an unpublished vulnerability during the attacks, which the researchers disclosed to Mozilla…