Mozilla's AI fuzzing finds hundreds of Firefox vulnerabilities
@eugeneyan highlights a Mozilla writeup showing AI models Mythos and Opus 4.6 found 271 and 22 Firefox vulnerabilities respectively, with Mozilla claiming no human-findable vulnerability category is beyond the model's reach.
Score breakdown
Security-focused AI/coding practitioners should watch Mozilla's approach as a concrete proof point that AI models can match human researchers across vulnerability categories — with Mythos yielding over 10× more findings than Opus 4.6 in the same codebase.
- 01Mythos found 271 vulnerabilities in Firefox, fixed in Firefox 150
- 02Opus 4.6 found 22 vulnerabilities in Firefox, fixed in Firefox 148
- 03Mozilla states no vulnerability category or complexity exists that humans can find but the model cannot
A post by @eugeneyan highlights a Mozilla writeup on using AI models for security vulnerability discovery in Firefox. Two models are cited: Mythos, which found 271 vulnerabilities that were fixed in Firefox 150, and Opus 4.6, which found 22 vulnerabilities fixed in Firefox 148 — a significant difference in yield between the two models.
Mozilla's conclusions from the effort are notably bold. The writeup is quoted as stating "so far we've found no category or complexity of vulnerability that humans can find that this model can't," suggesting AI-assisted fuzzing has reached parity with human security researchers across vulnerability types. Mozilla further claimed that "the defects are finite, and we are entering a world where we can finally find them all," framing AI-powered vulnerability discovery as a potential path to exhaustively eliminating security flaws in software.
Key facts
- 01Mythos found 271 vulnerabilities in Firefox, fixed in Firefox 150
- 02Opus 4.6 found 22 vulnerabilities in Firefox, fixed in Firefox 148
- 03Mozilla states no vulnerability category or complexity exists that humans can find but the model cannot
- 04Mozilla claims defects are finite and AI may enable finding all of them
- 05The writeup was published by Mozilla and highlighted by @eugeneyan on Twitter
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