Aztec’s Alpha V6 release, Tierra, fixes the critical V5 flaw. The foundation reports twice-as-fast proving on user devices and urges migration of funds and apps remaining on the old network.
Aztec Foundation announced Tierra, the Alpha V6 release of its privacy-focused Ethereum layer 2 network, on November 3. The foundation’s announcement says the upgrade fixes a critical proof-verification flaw in V5 and accelerates proof generation on users’ devices. It also reduces the time needed to deliver messages from Ethereum to Aztec.
Tierra lets developers combine public and private operations in the same application. Aztec says the network runs with more than 3,000 validators, without a centralized transaction sequencer or a privileged viewing key that can read all private transactions. The figure counts validators, not independent operators or users.
Why the V5 flaw required a network upgrade
The team found the flaw during an AI-assisted internal audit on July 27 and disclosed it on August 7. The flaw could let the network accept a proof for a transaction that violated its rules. The risk extended beyond privacy: blockchain state could be changed in an invalid way.
Aztec said it could not distinguish a valid proof in V5’s history from one accepted through the flaw. The team could not establish whether anyone had exploited the flaw or how much damage it might have caused. It did not confirm an attack or rule out losses. Developers changed Tierra’s proof circuits to prevent the faulty verification.
An Aztec spokesperson told The Block that fixing the issue required a network-wide upgrade because no single operator could apply the change alone. Developers use formal verification for Tierra’s core cryptographic components and AI-powered tools for security testing. Formal verification checks predefined properties mathematically. That check does not guarantee that every application on the network is free of bugs.
Aztec’s November 3 post on security and proof speed
The post loads from X when you open it.
One-second proofs and 12-second messages measure different steps
A zero-knowledge proof can demonstrate that computation follows the rules without revealing its private inputs. On Aztec, the user’s device executes the private part of a transaction and generates its proof; the network checks the submitted proof. The foundation’s one-second figure refers to proof generation in a native application on the device.
| Stage measured | Reported Tierra result | Limit of the comparison |
|---|---|---|
| Proof generation on the user’s device | As little as 1 second natively; twice as fast as the previous network | Not the time for the entire transaction to finalize on Ethereum |
| Message delivery from Ethereum to Aztec | Previously 2 minutes on average; now as little as 12 seconds | An old average is compared with a new minimum; not a fixed time for every transfer |
The foundation did not identify the device model, transaction type or detailed test conditions behind the one-second result. A user depositing through a blockchain bridge must also wait for source-chain confirmation, processing on the destination network and a spendable balance. The 12-second figure covers message delivery; it is not a completion time for every deposit or for withdrawals in the opposite direction.
In the Tierra and roadmap section beginning at 40:52 of Bankless’s November 3 interview, Aztec Foundation co-founder and CEO Zac Williamson discusses security work and faster proving. He lists faster withdrawals and finality, and lower proving costs, as the team’s next goals.
How private apps divide work between the device and the network
Developers use the Noir zero-knowledge programming language and Aztec.nr tools to choose which smart contract functions run privately and which run publicly, as Aztec explained in its September 21 architecture overview. Private functions execute on the user’s device; public functions execute on the network. A developer can combine both kinds in one contract and use them in a single transaction.
Private asset records are stored as encrypted “notes.” The wallet computes a transaction using the user’s notes and prepares a proof. It sends the proof, cryptographic records representing new notes, and markers that prevent spent notes from being reused. Only a note’s owner knows which note corresponds to its “nullifier” marker. Private amounts, counterparties and execution data stay on the device, while the state of public functions remains readable by everyone.
Transaction sequencers execute public computation and order transactions. Provers aggregate the proofs, and a contract on Ethereum verifies the aggregate. Required data is published in Ethereum’s data packages, known as blobs.
The foundation introduced eight applications launching or preparing to launch alongside Tierra. Aztec Labs’ zk.money focuses on private payments and savings, Galactica on running AI models with private data, and Nemi on private perpetual futures. Aztec describes Nulo as a browser wallet, Xochi as a way to trade using private intents that specify a user’s desired outcome, and Nyx as an application for private payments to any Ethereum wallet.
Olla is developing liquid staking for AZTEC, and Rolling Chat provides a private message board. The foundation did not give a common launch date for all eight applications. Aztec Labs co-founder and CEO Joe Andrews highlights deposits into zk.money directly from an Ethereum wallet. KriptoMeta did not test that deposit feature by transferring funds.
The official network status page, checked on November 4, lists Tierra as v6.0.0 at the Alpha stage, with no active security notices. In its November 3 update, the team still treats funds and applications remaining on V5 as exposed and urges migration to Tierra. Assessing rollup security also means checking whether data is available, who can upgrade the network and under what conditions users can withdraw assets.
