HomeCompaniesFabraix
Fabraix

The world's frontier hacker for AI agents.

Fabraix builds state-of-the-art AI red-teaming agents that continuously detect security vulnerabilities in customer-facing AI. Our product, Nyx, has already found vulnerabilities in agents at dozens of Fortune 500 companies. On AgentHarm, the leading benchmark for offensive AI security, Nyx achieved a 78% attack success rate, compared with 67% for GPT-5.6 Sol. Companies usually pay for penetration tests one project at a time. They select which systems to include, give a team a few weeks to find vulnerabilities, and receive a report when the project ends. Testing everything this way is very expensive. Globally, penetration tests cover only 26% of the software attack surface. AI agents can change more often than teams can test them. A new model, prompt, tool, permission, or data source can change what an agent does, even when the application code stays the same. The report describes only the version that was tested. AI is also increasing how much software companies produce and how often it changes. We built Nyx to automate this work. It does three things: 1. Nyx connects through the same interfaces customers use. It tests chat, voice, browser, and coding agents without source code or a special integration. 2. It draws on more than 10,000 jailbreaks that we have collected and classified, the largest such library we know of. 3. It uses each response to decide what to try next and can pursue a promising approach for hundreds of turns. In our tests, these adaptive attacks succeeded 20 times as often as attacks that were replayed unchanged or stopped after a fixed number of turns. Nyx often finds its first vulnerability within minutes or hours rather than days or weeks. Because the work is automated, companies can repeat the test with every change and at much lower cost. We're also the team behind ACE (Adversarial Cost to Exploit), a benchmark that measures AI security in terms of how much it costs attackers to break an AI system; providing a game-theoretic framework to understand how motivated a rational attacker would be in exploiting the system.
Active Founders
Ahmed Aly
Ahmed Aly
Founder
Co-founder @ Fabraix, building the frontier hacker for AI agents that finds failure modes and security exploits in AI systems before users do. Previously the first data scientist at Sequoia-backed Two, where he built a fraud engine from scratch processing $1B+ in annual B2B transactions, averting $50M in losses for multiple Fortune 150 companies. A published researcher with multiple papers in Q1 journals and a UCL PhD drop-out.
ibrahim abdu
ibrahim abdu
Founder
Founder at Fabraix. Previously SWE at Meta building AI agents to debug and fix production errors. Early engineer at Sequoia-backed startup Two B2B. Built proprietary compiler/database at TradingHub for algorithmic insider trading detection. BA in Philosophy, Politics and Economics from Oxford (ranked top 8% of cohort).
Company Launches
Fabraix: The Frontier Agent that Hacks Customer-facing AI.
See original launch post

TL;DR: Fabraix builds AI red-teaming agents that continuously detect security vulnerabilities in customer-facing AI. Our product, Nyx, has already found vulnerabilities in agents at dozens of Fortune 500 companies, and hits a 78% attack success rate on AgentHarm (leading offensive AI security benchmark) vs. 67% for GPT-5.6 Sol.

Ask: If your team ships customer-facing AI agents (chat, voice, browser, or coding) and needs to continuously test them for security vulnerabilities, find us at founders@fabraix.com.

https://www.youtube.com/watch?v=WHmJIMIuAEM

The Problem

AI agents introduce new vulnerabilities not present in traditional software..

In order for agents to be truly useful, they must be trusted to interact with untrusted surfaces like MCPs, websites and files, take real actions, and have access to confidential data. You can’t tell your defenses are sound by just reading your prompts since the agent's behaviour is not deterministic. The best thing to do is run your agent and really try to break it.  

Doing this red-teaming process manually is time consuming, costly, and you are unlikely to catch everything. And as soon as the agent is updated, you need to repeat it. Security teams simply don’t have the bandwidth to keep up with the rapid deployment inside organisations.

Our Solution

Nyx is our red-teaming agent that tests customer-facing AI agents, via direct interaction and also indirectly via its environment. It requires no access to your agent’s source code in order to test.

Nyx is highly adaptive when attacking. Rather than cycling through hard coded payloads like existing tools, it dynamically adjusts its attack strategies based on your agents defenses and responses. It probes your agent over a wide surface area of attack vectors, and deep dives This adaptive approach makes it 20x more effective as a red-teamer compared to other solutions.

We maintain a library of over 10,000 attack strategies and jailbreaks. These are high level strategies which are used by Nyx to generate dynamic adaptive attacks, over multiple turns. 

Every finding includes the attack steps, the agent’s responses, and the resulting failure for you to reproduce. You can then rerun the same test after a release to check whether the failure remains fixed. 

On the AgentHarm benchmark, Nyx achieved a 78% attack success rate, compared with 67% for GPT-5.6 Sol. Nyx has also found exploitable failures in public-facing agents operated by dozens of Fortune 500 companies.

We also built ACE (Adversarial Cost to Exploit), a benchmark that measures AI security in terms of how much it costs attackers to break an AI system; providing a game-theoretic framework to understand how motivated a rational attacker would be in exploiting the system.

The Team

We both have a lot of experience building and securing AI agents at scale.

Ibrahim built AI agents at Meta that diagnosed and fixed production errors. Before that, he built compilers and database engines in Fintech. He graduated from Oxford in the top 8% of his cohort.

Ahmed led international payments fraud team at Monzo. Before that, he was the first data scientist at a Sequoia-backed startup, where he built its fraud engine from scratch into processing more than $1B in annual B2B transactions and preventing tens of millions in losses for Fortune 150 companies. He has published several peer-reviewed research papers in Q1 journals.

We previously worked together, and have known each other for almost four years.

uploaded image

The Ask

If you ship a customer-facing (chat, voice, browser, or coding) agent, we can help you find all the failure modes and built a self-healing loop to discover, triage, and maintain secure AI agents.

founders@fabraix.com

Fabraix
Founded:2026
Batch:Summer 2026
Team Size:2
Status:
Active
Location:San Francisco
Primary Partner:Jon Xu