YC Summer 2026 (S26) founder

Xiaochuan Yu

Founder of Nebula Security, Autonomous AI defense system for cyber attack

Company

Xiaochuan Yu is listed as a founder of Nebula Security. Nebula Security is founded by the world’s #1 hacking team. We were the first team to build an nginx RCE and the first to root Android 17. Our co-founders include members of the world’s No. 1 CTF team, DEF CON winners, Black Hat speakers, and PhD in cybersecurity. We have won $400K in bug bounties by exploiting the Linux kernel and Chrome browser. “Audited by Nebula Security” is a mark of serious security credibility: a signal to customers, investors, and partners that your product has been reviewed by the world’s best hackers.

Founder traction evidence

Public posts and activity attributed directly to this founder.

  1. X

    Merry Christmas! Jailbreak for all arm64 iOS 16.0 to iOS 16.5 devices! https://t.co/Hg5sGK0Iwy

    Merry Christmas! Jailbreak for all arm64 iOS 16.0 to iOS 16.5 devices! https://t.co/Hg5sGK0Iwy

  2. X

    I am so proud that I am now driving the ultimate pwning machine at Nebula Security. Btw our team will be at Y Combinator Dogpatch site to...

    I am so proud that I am now driving the ultimate pwning machine at Nebula Security. Btw our team will be at Y Combinator Dogpatch site tomorrow, feel free to talk with us if you are interested in Vega (and probably more 0days?)

  3. X

    We spent a long time on this writeup. Hope you like it. One interesting thing is our human research team finishing the d8 shell exploit ...

    We spent a long time on this writeup. Hope you like it. One interesting thing is our human research team finishing the d8 shell exploit in <10min after Vega found this vulnerability. https://nebusec.ai/research/v8-cve-2026-6307-writeup/?p

  4. X

    Extremely brilliant, especially when security is full of AI shit.

    Extremely brilliant, especially when security is full of AI shit.

  5. X

    an interesting story i would like to share: I found 7 0days with gpt daybreak blue team version on flight to USENIX a few days ago.

    an interesting story i would like to share: I found 7 0days with gpt daybreak blue team version on flight to USENIX a few days ago. Leveraging its capabilities to do offensive security is quite easy.

  6. X

    Watch us cook @writegsqword

    Watch us cook @writegsqword

  7. X

    Sometimes, all you need to do is dropping a screenshot and let it speak for itself.

    Sometimes, all you need to do is dropping a screenshot and let it speak for itself.

  8. X

    Some people say that a goldfish's memory lasts only 7 seconds, so can a goldfish fully remember the process of our exploitation?

    Some people say that a goldfish's memory lasts only 7 seconds, so can a goldfish fully remember the process of our exploitation?