Vercel's $1M Sandbox challenge uncovered a Linux kernel zero-day and paid $242,000 in bounties

On October 14, 2026, Vercel published the results of its $1M Sandbox hacker challenge: 1,285 reports over two weeks, $242,000 in bounties and a Linux kernel zero-day that could leak host memory, crash the host or run code on it.

Archive entry: this covers an event from October 14, 2026, and we published it on November 8, 2026. The details come from sources dated at the time and may have changed since.

On October 14, 2026, Vercel published the results of its $1M hacker challenge for Vercel Sandbox, the isolated environment many agent products use to run code. According to Vercel's findings post on the Sandbox challenge, the challenge drew 1,285 reports over two weeks and uncovered a Linux kernel zero-day.

What the challenge found

The challenge launched in August and produced 1,285 reports over two weeks, and Vercel paid $242,000 in bounties.
On day three, Paulos Yibelo of pwn.ai found a defect in the Linux kernel's networking stack. Crafted packets sent from inside the microVM could leak host memory, crash the host or execute code on the host.
The memory leak was demonstrated against Vercel production sandboxes. The crash and code-execution attacks were demonstrated on the researcher's own KVM and Firecracker machines, set up like Vercel Sandbox.
Fixes were under private review and CVEs were pending.
Vercel said no report showed anyone accessing customer data in Vercel Sandbox.
A Vercel intern found a cross-tenant data leak in the Linux device-mapper storage layer that let a sandbox read recycled disk blocks from deleted sandboxes.

What it meant for people building with AI

Many AI app builders and agents ran untrusted code in microVM sandboxes like this one. The defect was in the Linux kernel's networking stack rather than in Vercel's own product, so the risk extended across shared infrastructure, not just Vercel.

Independent review and validated findings

Trail of Bits spent four engineer-weeks reviewing the source code and reported 20 findings. It concluded that the virtualization boundary was sound. The validated findings were 1 critical, 5 high, 9 medium, 42 low and 32 informative.

Sources

Findings from the $1M Vercel Sandbox challenge (Vercel, October 14, 2026, official)

Written with AI assistance, strictly from the sources listed above. Before it went live, automated checks verified its dates, sources and every language edition.