---
id: 5289
title: "Circuit Breaker: The Missing Constraint That Compromised RISC Zero’s zkVM"
source_domain: hackenproof.com
source_url: "https://hackenproof.com/blog/risc-zero-zkvm-missing-constraint-vulnerability"
published_at: "2026-06-11 10:03"
tags: ["bug-bounty", "web3", "vulnerability-research", "cryptography", "vulnerability", "zkvm", "zero-knowledge-proofs", "risc-zero", "riscv"]
phying_url: "https://phying.com/item/5289"
lang: en
---

# Circuit Breaker: The Missing Constraint That Compromised RISC Zero’s zkVM

## Summary

How a missing constraint in RISC Zero's rv32im circuit let a malicious prover forge results for 3-register RISC-V instructions like remu and divu in risc0-zkvm 2.x.

## Intelligence Metadata

- **Sources:** hackenproof.com
- **Published:** 2026-06-11 10:03
- **Original:** https://hackenproof.com/blog/risc-zero-zkvm-missing-constraint-vulnerability
- **Phying News:** https://phying.com/item/5289