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Jobs

• 2024/11 ~ current: Security Engineer at GMO Flatt Security
• 2023/09 ~ 2024/10: Security Engineer at 3-shake
• 2022/02 ~ 2023/08: SWE at STAR FESTIVAL
• 2020/05 ~ 2022/02: SWE at full-time employee
• 2020/01 ~ 2020/04: SWE at part-time job
• 2015/11 ~ 2016/12: SWE at part-time job

Skills

Certifications

• Certified Red Team Professional (CRTP) - June 2026
• OSWE (OffSec Web Expert) - October 2025
• Driver's License - December 2019

Credits

• CVE-2026-33810 Case-Sensitive DNS Name Constraint Bypass in Go crypto/x509

  • https://www.cve.org/CVERecord?id=CVE-2026-33810
  • https://pkg.go.dev/vuln/GO-2026-4866
  • https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU
  • https://flatt.tech/cve/2026-33810

• x/net/quic: remote panic via short dstConnID in retry token validation

  • https://github.com/golang/go/issues/78292

• Unauthenticated Path Traversal -> Arbitrary File Read (Repository & Host OS)

  • https://bughunters.google.com/reports/vrp/ZqsiiwS5f/report

• Blink CSSOM: renderer stack overflow via deeply nested CSSMathSum

  • https://issues.chromium.org/u/2/issues/517550063

• Hack The Box Omniscient Rank

  • https://labs.hackthebox.com/achievement/badge/1415870/219

Media

• 実務で担当するまでに独学した、攻撃者視点のセキュリティ

  • https://note.com/flatt_security/n/nb91c25832e7c?magazine_key=m13febbcd01c3

• 3名のOSWE合格記と資格取得支援について - セキュリティエンジニア鼎談

  • https://note.com/flatt_security/n/n7f452420249c?magazine_key=m13febbcd01c3

• Hello, Flattmate!｜セキュリティエンジニア てぃー

  • https://note.com/flatt_security/n/nf0b85a5ea355

• 攻めと守りで理解するPHPアプリケーションのセキュリティ：生成AI時代のXSSとその対策

  • https://developers.gmo.jp/technology/66864/
  • https://speakerdeck.com/flatt_security/gong-me-to-shou-ri-deli-jie-suru-php-apurikesiyon