Security1 hOctober 30, 2026, 06:02

Epoch AI: open-weight GLM 5.3 exploited six Firefox releases at ~$1,000 each

Epoch AI reported that Z.ai's open-weight GLM 5.3 autonomously exploited the browser patch gap to compromise six recent Firefox releases between September 17 and October 26, 2026, at roughly $1,000 per version in API costs. The model also rediscovered an unpublished sandbox-escape flaw, which Mozilla patched in Firefox 159.0 on October 27.

Unite.AI

Open source

Epoch AI: open-weight GLM 5.3 exploited six Firefox releases at ~$1,000 each

GLM 5.3 compromised Firefox 156.0 through 158.0.1; fastest attempt took 12 hours
Marginal cost per compromised version was about $1,000 at API pricing
Epoch AI spent over $100,000 in API costs on the Firefox research
Mozilla patched the disclosed flaw in Firefox 159.0 on October 27, 2026

#Z.ai#GLM#Mozilla#Firefox

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