Story perspectives

Mozilla Fixes 423 Firefox Bugs Using Anthropic AI

5/8/2026

Summary

Story summary

Mozilla fixed 423 Firefox bugs in April 2026 after Anthropic’s Mythos AI flagged 271 vulnerabilities.
Distinguished engineer Brian Grinstead credited a stronger model and a custom harness for the results.
The team disclosed 12 bugs, including a 20-year-old heap use-after-free flaw and sandbox escapes.
Davi Ottenheimer said his test found eight bugs in two minutes for $0.75 using cheaper models, with Mozilla’s bounty reaching $20,000 for sandbox bugs.

1 of 1

Story summary

Mozilla fixed 423 Firefox bugs in April 2026 after Anthropic’s Mythos AI flagged 271 vulnerabilities.
Distinguished engineer Brian Grinstead credited a stronger model and a custom harness for the results.
The team disclosed 12 bugs, including a 20-year-old heap use-after-free flaw and sandbox escapes.
Davi Ottenheimer said his test found eight bugs in two minutes for $0.75 using cheaper models, with Mozilla’s bounty reaching $20,000 for sandbox bugs.