Krux
March 7, 2026
Claude Found 22 Firefox Bugs in Two Weeks
Published: March 7, 2026 at 12:31 AM
Updated: March 7, 2026 at 12:31 AM
100-word summary
Anthropic's Claude Opus 4.6 scanned nearly 6,000 C++ files in Firefox and submitted 112 bug reports, uncovering 22 vulnerabilities including 14 labeled high-severity. Most fixes shipped in Firefox 148 last week. The AI excelled at spotting flaws but flopped at turning them into working exploits, succeeding in only two cases despite burning through thousands of API credits. Claude has now surfaced over 500 zero-days across open-source projects. The gap between finding bugs and weaponizing them suggests AI might accelerate security patching faster than it arms attackers.
What happened
Anthropic's Claude Opus 4.6 scanned nearly 6,000 C++ files in Firefox and submitted 112 bug reports, uncovering 22 vulnerabilities including 14 labeled high-severity. Most fixes shipped in Firefox 148 last week. The AI excelled at spotting flaws but flopped at turning them into working exploits, succeeding in only two cases despite burning through thousands of API credits. Claude has now surfaced over 500 zero-days across open-source projects.
Why it matters
The gap between finding bugs and weaponizing them suggests AI might accelerate security patching faster than it arms attackers.