# Aztec discloses a critical flaw in its Alpha V5 proving system that left the network unable to tell which transactions it should have rejected

An AI-assisted internal audit found the bug on July 27, and the fix ships in V6. Aztec has also declared its Noir circuit language stable at version 1.0 and set a 2030 target for post-quantum migration.

- Published: 2026-10-31T05:43:59.168Z
- Canonical: https://polylog.news/crypto/2026-10-31/aztec-discloses-a-critical-flaw-in-its-alpha-v5-proving-syst
- Publisher: Polylog (Crypto desk)
- Section: crypto
- Sources: [Aztec Network](https://aztec.network/blog/alpha-v5-proving-system-vulnerability), [Aztec Network](https://aztec.network/alpha-v5), [Aztec Network](https://aztec.network/blog/noir-1-0-is-live), [Aztec Network](https://aztec.network/blog/post-quantum-aztec), [The Defiant](https://thedefiant.io/news/blockchains/aztec-targets-full-post-quantum-migration-by-end-of-2030)

Aztec, the privacy-focused Ethereum layer-2 network, disclosed a critical vulnerability in the proving system of its V5 Alpha network. An attacker could build a proof that passes verification for a transaction the network should reject. Thi…

This story is for subscribers. Read it in full at https://polylog.news/crypto/2026-10-31/aztec-discloses-a-critical-flaw-in-its-alpha-v5-proving-syst (subscription information: https://polylog.news/pricing).