# Aztec reopens private payments with transfer caps while a proving-system flaw in Alpha V5 stays unfixed

Contributors say a forged proof could pass verification for an invalid transaction, and they cannot tell from chain history whether anyone has already used the flaw.

- Published: 2026-10-05T05:31:33.542Z
- Canonical: https://polylog.news/crypto/2026-10-05/aztec-reopens-private-payments-with-transfer-caps-while-a-pr
- 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), [Unchained](https://unchainedcrypto.com/aztec-revives-its-private-payments-wallet-capping-every-transfer-below-2500/), [Incrypted](https://incrypted.com/en/aztec-has-relaunched-the-private-wallet-zk-money/)

Aztec, the privacy-focused Ethereum layer-2 network, is running its Alpha V5 release with a critical defect in its proving system. In its [disclosure](https://aztec.network/blog/alpha-v5-proving-system-vulnerability), Aztec says core contributors found the flaw on July 27 through internal AI-assisted auditing. An attacker may be able to construct a proof that passes verification for a transaction the network should reject. If the network accepted that proof, the transaction could change state outside the rules V5 is meant to enforce. [Unchained](https://unchainedcrypto.com/aztec-revives-its-private-payments-wallet-capping-every-transfer-below-2500/) reported that the flaw was disclosed on August 7.

Contributors say they cannot determine whether anyone exploited the flaw before they found it. The [Alpha V5](https://aztec.network/alpha-v5) system does not record enough information to separate ordinary transactions from transactions accepted through the flawed proving path, so chain history cannot settle the question. Aztec told teams planning V5 deployments to pause. It told teams with live contracts to limit user exposure, isolate affected functions and be ready to move users to new deployments. The fix will arrive with V6, which will update the circuits (the arithmetic programs that define what a valid proof must show) so the network rejects proofs tied to the affected system. Aztec says human audits found no other high-severity issues in V5.

Aztec Labs nevertheless relaunched zk.money, its private payments wallet, on September 29, before V6 ships. Each deposit, payment and withdrawal is capped below $2,500, and a $50,000 daily deposit limit applies across all users, [Incrypted reported](https://incrypted.com/en/aztec-has-relaunched-the-private-wallet-zk-money/). Aztec Labs attributes the caps to new, experimental cryptography. The caps also limit how much an attacker could take through a forged proof.

## What this means

The exposure is structural. Most rollup security models assume that someone can detect an invalid state transition. A soundness bug in the prover defeats that assumption, because the invalid transaction looks valid to every verifier. Aztec's statement that it cannot tell whether the flaw was exploited is a plain admission that this class of failure cannot be audited after the fact. Users of zk.money carry the risk, and so do builders who deployed on V5. Holders of privacy-layer-2 tokens are exposed indirectly, because investors will discount any network whose correctness cannot be checked. The cap is a reasonable control because it limits how much one exploit can extract. The market still underrates the argument that privacy networks need several independent proof systems and a user withdrawal path that works even if the network stalls before deposits should grow. The desk's read is that Aztec keeps the caps until V6 ships and that other zero-knowledge rollups add similar per-transaction limits or second provers within months. A V6 release that lifts the caps without an independent proof-system review would show the read is wrong.

## What to watch

- The V6 release date and whether an outside party audits the new circuits. An independent review is the only evidence that the flawed proving path is closed.
- Whether Aztec raises the zk.money caps before V6 ships. Lifting them early would show that growth is taking priority over containing the known flaw.
- Disclosures of similar soundness defects in other proving systems that teams found with AI-assisted review. A cluster of them would confirm that this is a recurring risk class rather than a single team's mistake.