Epoch AI Researchers Say GLM 5.3 Exploits Six Firefox Releases for $1,000 Each

Epoch AI researchers report that Z.ai's open-weight GLM 5.3 turns security fixes published before they ship into working exploits for six Firefox releases, versions 156.0 through 158.0.1, at about $1,000 per compromise. Mozilla patched a related unpublished flaw in Firefox 159.0 on Oct. 27.

• Epoch AI says GLM 5.3 built its fastest working Firefox exploit in 12 hours, against a 48 hour limit.
• Researchers report no refusals or safeguards from any provider, including Z.ai, during the exploit runs.
• Epoch AI says the attack could read passwords and cookies stored on machines of Firefox's more than 200 million users.