The Zcash Foundation reported four Zebra releases between September 21 and October 5: three updates in the 6.4.x series and the first release candidate for Zebra 7.0.0. The releases included security and reliability fixes, while NU7 moved to Zcash’s public Testnet ahead of a tentative mainnet activation in 2026.
- 6.4.2 fixed a bug that could crash Zebra when it received a malformed transaction.
- Zebra 7.0.0-rc.0 supported NU7’s activation on Testnet on October 4.
- Operators will need a release that supports NU7 before the 6.4.x line ends in early November.
- NU7’s mainnet activation is tentatively scheduled for November 5, 2026.
Four releases focused on readiness and reliability
In an engineering update covering September 21 to October 5, the Zcash Foundation described a busy stretch for Zebra, its Rust-based independent full-node implementation for Zcash. A full node helps run the network by processing and maintaining blockchain data.
The four releases were Zebra 6.4.0, 6.4.1 and 6.4.2, followed by Zebra 7.0.0-rc.0. The update does not provide a date for each release, but says 6.4.0 and 6.4.1 came out on the same day.
The Foundation described Zebra 6.4.0 as a security release. It added an experimental gRPC server compatible with lightwalletd, lowered the ZIP 317 conventional fee and sped up block-template delivery for miners.
The gRPC addition provides an interface for software to communicate with Zebra. Its compatibility with lightwalletd could support wallet-service infrastructure, but the release description does not say that wallets can connect directly or explain how widely the interface will be used.
The ZIP 317 change affects the conventional transaction fee setting, not Zcash’s consensus rules. The Foundation’s update does not say how much the fee was lowered, so this should not be read as a network-wide change to the economics of Zcash.
Zebra 6.4.1 fixed a potential synchronization stall near the chain tip, the current end of the blockchain. Zebra 6.4.2 addressed a more direct reliability risk: a malformed transaction from a peer could crash Zebra. Google’s OSS-Fuzz, which tests open-source software by feeding it unexpected inputs, found the bug.
The finding shows that node security is not only about sophisticated attacks. A software defect can also disrupt an implementation. The reported issue affected Zebra, but does not establish that every Zcash node implementation was affected.
NU7 reaches public Testnet
Zebra 7.0.0-rc.0 is the first release candidate for NU7, Zcash’s upcoming network upgrade. NU7 was activated on Zcash’s public Testnet on October 4 at block 4, 465, 026, using the release candidate.
A testnet is a separate network where developers can test software and upgrade procedures before they reach mainnet, the production network. Testnet activation is a useful step, but it does not guarantee that a release candidate is final or that a planned mainnet date will hold.
The Foundation’s update does not describe NU7’s specific protocol changes. That makes the upgrade’s technical and user impact difficult to assess from this milestone alone.
The Foundation planned another Zebra release for the following week, expected to include NU7 support, but did not give an exact release date. It also said the 6.4.x line would stop in early November. Operators should install the NU7-supporting release before then and check the latest release guidance.
The cutoff details need clarification. The update says 6.4.1 halts around November 2, while also saying the 6.4.x line stops in early November. It does not explain whether “halts” refers to a specific software behavior, a support deadline or another operational milestone. Zebra 6.4.2 had already been released, too. Operators should not treat November 2 as a confirmed universal deadline without checking the current instructions for their software version.
NU7’s mainnet activation is tentatively scheduled for November 5, 2026. That remains a target, not a guarantee. Testing and release readiness will determine whether it holds. A draft NU7 proposal also sets out a target mainnet height, while Grayscale’s Zcash product share split is another development as the upgrade approaches.
Key questions and answers
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How many Zebra releases did the Foundation report?
Four: three 6.4.x updates and Zebra 7.0.0-rc.0, the first release candidate for version 7.0.0.
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What did the 6.4.x updates address?
They added an experimental lightwalletd-compatible gRPC interface, lowered the ZIP 317 conventional fee, improved block-template delivery for miners, fixed a potential sync stall and addressed a malformed-transaction crash in Zebra.
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When did NU7 reach public Testnet?
October 4, at block 4, 465, 026, using Zebra 7.0.0-rc.0.
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When is NU7 expected on mainnet?
Its activation is tentatively scheduled for November 5, 2026. The date could change, and the update does not specify NU7’s protocol changes.
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What should Zebra operators do?
Install the upcoming release with NU7 support before the 6.4.x line ends in early November. The cutoff details are unclear, so operators should check the Foundation’s current release guidance for their version. Separate Orchard privacy concerns are a reminder to scrutinize protocol and software risks.
