Zebra 6.0.0-rc.0

Added

• Support for the NU6.3 "Ironwood" shielded pool and v6 transaction format,
  activating on Testnet at height 4,134,000. The consensus parameters (v6 version
  group ID, consensus branch ID, and Testnet activation height) match
  zcash_protocol. No Mainnet activation height is set yet.
• The z_gettreestate, z_getsubtreesbyindex, and verbose getblock RPCs expose the
  Ironwood note commitment tree and its subtree roots from NU6.3 activation
  (#10888).
• Zebra now tags the coinbase input of every block it mines with a 🦓. The
  mining.extra_coinbase_data option is now limited to 86 bytes (was 94); Zebra
  refuses to start if it is exceeded.
• Pre-built zebrad binaries are attached to each GitHub release for Linux on
  x86_64 and aarch64, so operators can run a node without Docker or a source
  build, also installable with cargo binstall zebrad. Each .tar.gz carries a
  SHA-256 checksum, a Sigstore build-provenance attestation, and a Cosign signature
  over the checksum manifest (#10799)
• Added a Regtest configuration option, should_allow_unshielded_coinbase_spends,
  to forbid spending coinbase outputs into transparent outputs (the inverse of
  zcashd's -regtestshieldcoinbase). It defaults to allowing such spends, preserving
  existing Regtest behavior (#10698)
• When the indexer RPC is enabled, a co-located read-state consumer can follow the
  node more efficiently: the non-finalized block subscription resumes from the
  consumer's known chain tips instead of re-streaming the whole non-finalized state,
  and a new GetBlock indexer method lets the consumer fetch blocks it is missing
  while its finalized state catches up.
• New zebra-state read request ReadRequest::FindForkPoint (with response
  ReadResponse::ForkPoint) that returns the most recent block in a caller-supplied
  locator that is on the best chain — the fork point — for clients tracking chain
  reorganizations through a read-only state service.
• Added a [notify] block_notify_command option that runs a command on each best-chain-tip
  change, with %s replaced by the new block hash — Zebra's equivalent of zcashd's
  -blocknotify.

Changed

• The state database format is bumped to 28.0.0 for the NU6.3 "Ironwood" shielded
  pool. This is a major-version bump that is restorable in place from the previous
  major format version (no resync): an in-place migration backfills the genesis
  Ironwood note commitment tree and anchor, four new (initially empty) ironwood_*
  column families are created, and the chain value pool record is widened to include
  the Ironwood pool. The getblockchaininfo and getblock valuePools now include
  the (zero, until NU6.3 activates) ironwood pool.
• Opening a Zebra state read-only (for example, as a secondary instance over a
  running node's database) now fails with a clear error instead of panicking when
  the cache directory is missing or unreadable, when no database exists at the
  configured path, or when an ephemeral database is also configured (a read-only
  secondary must not delete the primary's files). The read-write open path is
  unchanged.
• Upgraded the librustzcash crate cohort to the NU6.3 pre-release wave (orchard
  0.15.0-pre.1, zcash_address 0.13.0-pre.0, zcash_history 0.5.0-pre.0, zcash_keys
  0.15.0-pre.0, zcash_primitives 0.29.0-pre.0, zcash_proofs 0.29.0-pre.0,
  zcash_protocol 0.10.0-pre.0, zcash_transparent 0.9.0-pre.0) for v6 transaction
  and Ironwood support (#10762).
• Bumped anyhow to 1.0.103, clearing RUSTSEC-2026-0190
  (#10849).

Fixed

• getblocktemplate now caches the built coinbase transaction per block, so repeated short-poll
  requests within the same block no longer rebuild it. This prevents CPU saturation and multi-second
  template latency when mining to a shielded (Sapling or Orchard) address
  (#10847)
• Released zebrad binaries report their source commit in zebrad version
  (#10798)
• Handle invalidateblock and reconsiderblock edge cases (chain-root and
  same-height sibling-tip invalidation, repeated reconsideration) without panicking
  (#10586)
• A timeout waiting for a transparent input UTXO during transaction verification is
  now treated as a missing input instead of an internal error, preventing a sync
  stall near the chain tip (#10810)
• The co-located read-state syncer (used by indexers like Zaino) no longer drops and
  re-creates its non-finalized block subscription every second while its view of the
  finalized state lags the node's
  (#10818)

Security

• Use constant-time comparison for RPC cookie authentication (#10567)
• Zebra's release Docker images are now reproducible: an independent rebuild of a
  published zebrad from the same commit produces the same binary. The Rust
  toolchain and the Rust and Debian base images are pinned by exact version and
  digest, and build paths and file timestamps are normalized, so two independent
  builds of the same commit produce the same binary. Release images are also built
  without the shared build cache, so a published image cannot inherit a layer from
  a lower-trust build
  (#10798)
• Release Docker images are signed and carry build provenance and a signed SBOM.
  Each production release gets a Cosign keyless signature, a signed SLSA provenance
  attestation, and a signed SBOM, so anyone can confirm an image came from Zebra's CI
  with cosign verify or gh attestation verify
  (#10798)
• Route directly pushed transactions (tx messages) through the same per-peer
  mempool admission accounting as advertised transaction IDs, so a single inbound
  peer cannot bypass the per-peer download cap by pushing full transactions
  instead of advertising them
  (GHSA-m9xx-8rcj-vmgp).
  This is the direct-push counterpart of the advertisement-path fix in
  GHSA-4fc2-h7jh-287c. Thanks to @SuplabsYi for reporting the issue.
• Fixed a panic in the getblock RPC at verbosity 2 for blocks not in the best
  chain: their transactions' confirmations are negative and were cast to an
  unsigned type
  (GHSA-x6v8-c2xp-928m).

Contributors

Thank you to everyone who contributed to this release, we couldn't make Zebra without you:
@andres-pcg, @conradoplg, @dannywillems, @emersonian, @gustavovalverde, @nuttycom, @syszery, @upbqdn and @zmanian.