Youngjoon Kim

I am a postdoctoral researcher at SSLab, School of Cybersecurity and Privacy, Georgia Tech, working with Professor Taesoo Kim. My research focuses on AI-driven automated vulnerability discovery and repair via Cyber Reasoning Systems (CRS), combining LLMs with program analysis techniques.

As a member of Team Atlanta, I won 1st place in the DARPA AI Cyber Challenge (AIxCC) Finals, where our CRS found 43 vulnerabilities including 6 zero-days. I am currently a main contributor to OSS-CRS.

I received my Ph.D. in Information Security from Korea University under the supervision of Professor Jiwon Yoon (Thesis: AI-Driven Automated Vulnerability Discovery and Repair). Previously, I served as a captain in the R.O.K. Army, working at the Agency for Defense Development (ADD) and the R.O.K. Cyber Operations Command, gaining experience in both security research and security engineering.

My main research interest is LLM agent-based offensive security. More broadly, my interests include fuzzing, automated program repair, LLM-based security analysis, and offensive security.

News

Aug 2026	Our paper COIN was accepted to EMNLP 2026!
Aug 2026	As a member of Blue Water, I won 1st place at DEF CON 34 CTF Finals!
Jun 2026	Our paper CtxFuzz was accepted to ASE 2026!
May 2026	Our paper SoK: DARPA’s AI Cyber Challenge was accepted to USENIX Security 2026!
Apr 2026	Our paper OSS-CRS was accepted to USENIX WOOT 2026!
Aug 2025	Team Atlanta won 1st place in the DARPA AI Cyber Challenge (AIxCC) Finals! Our CRS found 43 vulnerabilities including 6 zero-days.
May 2025	Our paper “Logs In, Patches Out: Automated Vulnerability Repair via Tree-of-Thought LLM Analysis” was accepted to USENIX Security 2025!

Publications

EMNLP

COIN: A Live, Large-scale Benchmark for Semantics-to-Input Code Reasoning

Jiho Kim, Cen Zhang, Youngjoon Kim, and 4 more authors

In The 31st Conference on Empirical Methods in Natural Language Processing (EMNLP 26). To appear , 2026

Bib

@inproceedings{kim2026coin,
  title = {COIN: A Live, Large-scale Benchmark for Semantics-to-Input Code Reasoning},
  author = {Kim, Jiho and Zhang, Cen and Kim, Youngjoon and Kim, Dongkwan and Lee, Brian Junekyu and Jeong, Dae R. and Kim, Taesoo},
  booktitle = {The 31st Conference on Empirical Methods in Natural Language Processing (EMNLP 26)},
  year = {2026},
}

ASE

CtxFuzz: Context-Aware Directed Fuzzing via Runtime Fuzzer–Agent Cooperation

Jiho Kim, Dongkwan Kim, HyungSeok Han, and 6 more authors

In IEEE/ACM International Conference on Automated Software Engineering (ASE 26). To appear , 2026

Bib HTML

@inproceedings{kim2026ctxfuzz,
  title = {CtxFuzz: Context-Aware Directed Fuzzing via Runtime Fuzzer–Agent Cooperation},
  author = {Kim, Jiho and Kim, Dongkwan and Han, HyungSeok and Kim, Youngjoon and Park, Soyeon and Ji, Sangwoo and Wang, Joshua and Jeong, Dae R. and Kim, Taesoo},
  booktitle = {IEEE/ACM International Conference on Automated Software Engineering (ASE 26)},
  year = {2026},
}

Electronics Letters

SPACEPROTONET: Revealing Unknown Protocols’ Origin in Space Communications

Minchul Kim, Youngjoon Kim, Hyunjae Cho, and 4 more authors

IET Electronics Letters, 2026

Bib HTML

@article{kim2026spaceprotonet,
  title = {SPACEPROTONET: Revealing Unknown Protocols' Origin in Space Communications},
  author = {Kim, Minchul and Kim, Youngjoon and Cho, Hyunjae and Kim, Kwangsoo and Ryu, Han-Eul and Jeong, Jinwoo and Yoon, Jiwon},
  journal = {IET Electronics Letters},
  year = {2026},
}

SEC

SoK: DARPA’s AI Cyber Challenge (AIxCC): Competition Design, Architectures, and Lessons Learned

Cen Zhang, Younggi Park, Fabian Fleischer, and 18 more authors

In 35th USENIX Security Symposium (USENIX Security 26), 2026

Bib HTML

@inproceedings{zhang2026sok,
  title = {SoK: DARPA's AI Cyber Challenge (AIxCC): Competition Design, Architectures, and Lessons Learned},
  author = {Zhang, Cen and Park, Younggi and Fleischer, Fabian and Fu, Yu-Fu and Kim, Jiho and Kim, Dongkwan and Kim, Youngjoon and Xu, Qingxiao and Chin, Andrew and Sheng, Ze and Zhao, Hanqing and Pelican, Michael and Musliner, David J. and Huang, Jeff and Silliman, Jon and Mcdaniel, Mikel and Casavant, Jefferson and Goldthwaite, Isaac and Vidovich, Nicholas and Lehman, Matthew and Kim, Taesoo},
  booktitle = {35th USENIX Security Symposium (USENIX Security 26)},
  year = {2026},
}

WOOT

OSS-CRS: Liberating AIxCC Cyber Reasoning Systems for Real-World Open-Source Security

Andrew Chin, Dongkwan Kim, Yu-Fu Fu, and 7 more authors

In 20th USENIX WOOT Conference on Offensive Technologies (WOOT 26), 2026

Bib HTML Code

@inproceedings{chin2026osscrs,
  title = {OSS-CRS: Liberating AIxCC Cyber Reasoning Systems for Real-World Open-Source Security},
  author = {Chin, Andrew and Kim, Dongkwan and Fu, Yu-Fu and Fleischer, Fabian and Kim, Youngjoon and Han, HyungSeok and Zhang, Cen and Lee, Brian Junekyu and Zhao, Hanqing and Kim, Taesoo},
  booktitle = {20th USENIX WOOT Conference on Offensive Technologies (WOOT 26)},
  year = {2026},
}

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