2026-05-07

Claude Mythos Preview

even with caveats, this is a striking datapoint for AI-assisted security triage/fix throughput in a real major codebase.

Original source

Reading Log X Post Historical Backfill Security Org Design

Imported from historical reading log.

  • Extracted Alex Albert's post via api.fxtwitter.com fallback and read the attached chart.
  • Claim: with help from Claude Mythos Preview, the Firefox team fixed more security bugs in April 2026 than in the previous 15 months combined.
  • The screenshot supports the magnitude: Firefox Security Bug Fixes by Month shows a jump from ordinary monthly counts in the ~17–31 range through 2025, then 61 in Feb 2026, 76 in Mar 2026, and a huge spike to 423 in Apr 2026.
  • Caveat worth keeping in mind: the chart is labeled All Sources · All Severities, so this is broader than just critical vulns, and the post does not explain methodology beyond the attribution to Claude assistance.
  • Why it matters: even with caveats, this is a striking datapoint for AI-assisted security triage/fix throughput in a real major codebase.
  • Good angle: the first widely persuasive AI coding wins may come from backlog demolition in security and maintenance work, not greenfield feature building.