---
id: 5667
title: "Unfaithful claims: breaking 6 zkVMs"
source_domain: osec.io
source_url: "https://osec.io/blog/zkvms-unfaithful-claims/"
published_at: "2026-03-03T12:00:00Z"
tags: ["web3", "vulnerability-research", "cryptography", "vulnerability", "zero-knowledge", "zkvm", "fiat-shamir", "soundness"]
phying_url: "https://phying.com/item/5667"
lang: en
---

# Unfaithful claims: breaking 6 zkVMs

## Summary

OtterSec breaks soundness in six zkVMs — Jolt, Nexus, Cairo-M, Ceno, Expander, Binius64 — where unbound prover values let attackers prove false statements after seeing Fiat-Shamir challenges.

## Intelligence Metadata

- **Sources:** osec.io
- **Published:** 2026-03-03T12:00:00Z
- **Original:** https://osec.io/blog/zkvms-unfaithful-claims/
- **Phying News:** https://phying.com/item/5667