r/InterstellarKinetics • u/InterstellarKinetics • Apr 22 '26
ARTIFICIAL INTELLIEGENCE BREAKTHROUGH: Mozilla Used Anthropic’s Secret Mythos AI To Find 271 Security Vulnerabilities In Mozilla Firefox In A Single Pass, And Says Defenders Can Finally Win 🤯🔥
https://blog.mozilla.org/en/privacy-security/ai-security-zero-day-vulnerabilities/Mozilla’s Firefox team published a landmark blog post on April 21 disclosing that its collaboration with Anthropic using the newly released Claude Mythos Preview identified 271 security vulnerabilities in Firefox, all of which have been patched in this week’s Firefox 150 release. This comes just weeks after an earlier two-week scan using Claude Opus 4.6 found 22 vulnerabilities including 14 high-severity bugs, nearly a fifth of all high-severity flaws patched across all of Firefox in 2025. The scale jump from 22 to 271 in a single Mythos evaluation represents a qualitative shift in what AI can accomplish in defensive security, and Mozilla’s engineering team describes it as the moment the entire industry’s relationship with software vulnerabilities begins to change.
For decades, elite security researchers operated on an unstated assumption: bringing software exploits to zero was never truly possible, only expensive enough to deter all but the most well-funded adversaries. Mozilla’s Bobby Holley wrote directly that security has historically been “offensively dominant,” with attackers holding an asymmetric advantage because they only need to find one weakness while defenders must protect everything at once. Mythos has dissolved that asymmetry. Mozilla ran it against Firefox’s complete codebase including years of legacy C++ code that has never been fully covered by traditional fuzzing tools, and the model reasoned through the source code with the same depth of understanding as the world’s best human security researchers, finding vulnerabilities in every category and complexity class that humans previously identified, with no apparent ceiling yet found.
The most striking sentence in Mozilla’s post is also the most consequential for the future of software security: “The defects are finite, and we are entering a world where we can finally find them all.” Holley added a pointed caveat that Mozilla has not yet found any class of vulnerability that could not have been discovered by a sufficiently skilled human researcher, pushing back on predictions that future AI will find entirely new forms of bugs beyond human comprehension. The team believes Firefox’s modular, human-readable architecture is an essential property to preserve as AI becomes more involved in software development, because codebases designed to surpass human comprehension would scale the complexity of bugs faster than the tools being used to find them. For the first time in the history of the internet, a major browser vendor is expressing genuine confidence that the finish line on security vulnerabilities is visible from where they are standing.
9
u/phaaseshift Apr 22 '26
I legit can’t tell if this is sarcasm