Nebula Security (YC S26) — Autonomous AI defense system for cyber attack
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.
Nebula Security is a Y Combinator company in the Summer 2026 batch. Its directory entry describes it as: Autonomous AI defense system for cyber attack. The founders listed are Eten Zou (Founder/CEO), Yuan Tan (Founder), Frank Wu (Founder/Security Research Lead) (Y Combinator directory entry, July 2, 2026).
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What it does Autonomous AI defense system for cyber attack (source)
Example from a real report (our sample on Target): “In March 2026, Target announced a planned incremental $1 billion operating investment” Source: Target Corporation (press release)
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.
Read from the page's own HTML and response headers on 10 September 2026, at https://nebusec.ai/. Each badge matched a string the site serves about itself — hover one to see which. Nothing here is a traffic, ranking or revenue figure: those cannot be read off a page and are not claimed.
Checked away from the directory entry. What is below does not come from the company's Y Combinator page.
NebuSec builds Nebu, an AI security platform for continuous code and cloud protection, backed by researchers who find zero-days in Chrome and Linux.
The title and description the site itself served, answering 200. Not a cached copy and not the company's directory entry — what was live when we asked.
Eten Zou
Founder/CEO
CEO & Founder @ Nebula Security (YC S26). PhD in Cybersecurity.
Focus on automated vulnerability research.
Yuan Tan
Founder
Founder at Nebula Security (YC S26). Black Hat USA speaker. PhD dropout in System Security with experience in DARPA-funded fundamental research on program analysis.
Frank Wu
Founder/Security Research Lead
Founder of Nebula Security (YC S26). Black Hat USA speaker and DEF CON finalist with r3kapig, the world's No. 1 hacking team in 2025. He led the DARPA AIxCC automated program repair team and shipped end-to-end RCE/LPE exploit chains on Chrome, Firefox, Linux, and Android. He pwned Google's kernelCTF multiple times with zero-days, and has published research at top academic venues such as USENIX Security and NDSS. Ph.D. dropout.
Xiaochuan Yu
Founder/CTO
Founder at Nebula Security (YC S26). Hacked into iPhone, Chrome, Firefox, Safari, QEMU, and various things in your daily life. DEFCON finalist for 3 consecutive years. $200k+ Bug Bounty in Chrome. Core member of r3kapig, the #1 hacking team in the world in 2025, on CTFTime. M.S. from UC San Diego. Research published at USENIX Security, BlackHat USA. Ph.D. droped out.
Founders, titles and bios as the company published them. Photographs are our own copies of the ones on that record, so they do not break when the original link expires.
No investor is drawn from a Form D — the form states how many invested and never who. The one investor on this graph is named because a batch has exactly one.
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Example from a real report (our sample on Target): “In March 2026, Target announced a planned incremental $1 billion operating investment” Source: Target Corporation (press release)
A Full Report on Nebula Security: verified, sourced, every claim cited, ready in a few minutes. See pricing.
What the Full Report on Nebula Security covers
The Short Answer
Which Company This Is
What They Do, And How The Money Works
Who Runs It, And How To Reach Them
The Money: Funding, Valuation, Runway
Who Pays Them, And Who They Are Up Against
Warning Bells
Sources
10 cited sources found
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