---
title: "Circuit and verifier version drift"
description: "The deployed verifying key no longer corresponds to the audited circuit, because of a recompilation, a toolchain upgrade, or a manual key copy."
type: "failure-mode"
url: "https://zkpick.com/audit/failure-modes/circuit-and-verifier-version-drift/"
section: "03 Auditing a ZK protocol"
authors:
  - "MarketComp"
publisher: "MarketComp"
version: "1.3"
updated: "2026-09-12"
license: "CC-BY-4.0"
json: "https://zkpick.com/data/audit/failure-modes/circuit-and-verifier-version-drift.json"
---

*By MarketComp. Updated 2026-09-12. Version 1.3. CC BY 4.0.*

# Circuit and verifier version drift

The deployed verifying key no longer corresponds to the audited circuit, because of a recompilation, a toolchain upgrade, or a manual key copy. Nothing detects the mismatch until proofs fail — or worse, until they succeed against the wrong relation.

**Mitigation:** Pin the hash of circuit artefacts and verifying keys in CI and on-chain, fail the build on mismatch, and make the deployed key hash publicly checkable against the audited commit.