CVE-2026-104435

Zebra 4.4.0 Consensus Divergence via V5 SIGHASH_SINGLE Without Output

Zebra zebrad 4.4.0 and zebra-script 6.0.0 fail to enforce a ZIP-244 consensus rule, accepting V5 transparent inputs signed with SIGHASH_SINGLE that lack a corresponding output. Attackers can broadcast crafted V5 transactions with more inputs than outputs that Zebra accepts but zcashd rejects, causing a network consensus split.

CVSS 4.0 · 8.3 High EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra

CVE-2026-104434

Zebra before 8.0.0 Denial of Service via z_listunifiedreceivers RPC

ZcashFoundation Zebra zebra-rpc before 8.0.0 and zebrad before 4.5.0 contain a reachable assertion in the z_listunifiedreceivers RPC handler, which calls expect() on Sapling receiver parsing that fails for Unified Addresses carrying invalid Jubjub points. Authenticated RPC clients can submit such an address to abort the zebrad process, repeatably keeping the node offline.

CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra

CVE-2026-104430

Zebra 4.5.0 Consensus Split via P2SH Sigop Overcount

Zebra zebrad 4.5.0 and zebra-script 7.0.0 count P2SH redeem script signature operations in legacy mode rather than zcashd's accurate P2SH mode, overcounting CHECKMULTISIG preceded by OP_1 through OP_16 as 20 sigops and causing a consensus divergence. Remote attackers can broadcast P2SH spends using low-threshold multisig redeem scripts so that a block zcashd accepts exceeds Zebra's inflated MAX_BLOCK_SIGOPS count, causing Zebra nodes to reject it and stall off the chain.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra

CVE-2026-104426

Zebra before 6.1.0 Quadratic Complexity DoS via Block Transparent Value Check

Zebra before 6.1.0 contains an inefficient algorithmic complexity vulnerability in remaining_transaction_value that clones the entire block-level spent-UTXO map per transaction during contextual verification. Attackers can mine or seed the mempool with roughly 26,000 minimal single-input transactions in one block, stalling every validating node for over 52 seconds.

CVSS 4.0 · 8.2 High EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra

CVE-2026-104425

Zebra before 6.1.0 Batch-Verification Poisoning DoS via Unattributed Pushed Transactions

ZcashFoundation Zebra before 6.1.0 contains a resource exhaustion vulnerability that allows unauthenticated peers to degrade block processing by pushing transactions with invalid Orchard proofs without being misbehavior-scored. Attackers can repeatedly push invalid proofs into the shared halo2 batch verifier, forcing honest block proofs onto the slow individual-verification path and slowing block processing roughly sevenfold.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra

CVE-2026-104423

Zebra before 6.2.1 Denial of Service via Uncapped V6 Shielded Proof Verification

Zebra (zebrad) before 6.2.1 contains an asymmetric resource consumption vulnerability that allows unauthenticated peers to stall block verification by pushing V6 mempool transactions with invalid Halo2 proofs. Attackers can flood the shared unprioritized Halo2 verification queue with zero-fee transactions carrying zero-filled Orchard and Ironwood proofs, causing nodes to fall behind the chain tip.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra

CVE-2026-104431

Zebra before 6.0.0 Denial of Service via Synchronous Script FFI Verification

Zebra before 6.0.0 contains a denial of service vulnerability that allows unauthenticated peers to stall Tokio workers by submitting mempool transactions requiring expensive synchronous script verification. Attackers can send non-standard high-sigop P2SH transactions that reach CachedFfiTransaction::is_valid() before standardness checks, saturating the verifier buffer and rendering the node unresponsive.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra

CVE-2026-104429

Zebra before 6.0.0-rc.0 Per-Peer Mempool Admission Bypass via P2P tx Messages

Zebra (zebrad) 5.0.0 before 6.0.0-rc.0 does not apply its per-peer mempool admission cap to transactions received as direct P2P tx messages, because these are queued without the sending peer recorded as their source. A remote inbound peer can push many unique transactions to occupy a disproportionate share of mempool admission slots, crowding out honest peers' transaction relay.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra

CVE-2026-104421

Zebra before 6.2.1 Block Download Denial of Service via KnownBlock SentHashes Lockout

Zebra before 6.2.1 contains an incomplete cleanup vulnerability that allows unauthenticated peers to block downloading of valid blocks by leaving rejected hashes in SentHashes. Attackers can send a contextually invalid block sharing an honest block's header hash, causing Request::KnownBlock to skip the honest block and keep nodes behind the tip.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra

CVE-2026-44498

ZEBRA: Block Validator Undercounts Coinbase and P2SH Sigops

ZEBRA is a Zcash node written entirely in Rust. Prior to version 4.4.0, Zebra's block validator undercounts transparent signature operations against the 20000-sigop block limit (MAX_BLOCK_SIGOPS), allowing it to accept blocks that zcashd rejects with bad-blk-sigops. A miner who produces such a block can split the network: Zebra nodes follow the offending chain while zcashd nodes do not. This issue has been patched in version 4.4.0.

CVSS 4.0 · 9.2 Critical EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebrad

CVE-2026-41583

ZEBRA: Consensus Divergence in Transparent Sighash Hash-Type Handling

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.1 and prior to zebra-script version 5.0.2, after a refactoring, Zebra failed to validate a consensus rule that restricted the possible values of sighash hash types for V5 transactions which were enabled in the NU5 network upgrade. Zebra nodes could thus accept and eventually mine a block that would be considered invalid by zcashd nodes, creating a consensus split between Zebra and zcashd nodes. In a similar vein, for V4 transactions, Zebra mistakenly used the "canonical" hash type when computing the sighash while zcashd (correctly per the spec) uses the raw value, which could also crate a consensus split. This issue has been patched in zebrad version 4.3.1 and zebra-script version 5.0.2.

CVSS 4.0 · 9.3 Critical EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra-script Zebrad

CVE-2026-41584

ZEBRA: rk Identity Point Panic in Transaction Verification

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.1 and prior to zebra-chain version 6.0.2, Orchard transactions contain a rk field which is a randomized validating key and also an elliptic curve point. The Zcash specification allows the field to be the identity (a "zero" value), however, the orchard crate which is used to verify Orchard proofs would panic when fed a rk with the identity value. Thus an attacker could send a crafted transaction that would make a Zebra node crash. This issue has been patched in zebrad version 4.3.1 and zebra-chain version 6.0.2.

CVSS 4.0 · 9.2 Critical EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra-chain Zebrad

CVE-2026-44497

ZEBRA: Consensus Divergence in Transparent Sighash Hash-Type Handling due to Stale Buffer

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.4.0 and prior to zebra-script version 6.0.0, the fix for CVE-2026-41583 introduced a separate issue due to insufficient error handling of the case where the sighash type is invalid, during sighash computation. Instead of returning an error, the normal flow would resume, and the input sighash buffer would be left untouched. In scenarios where a previous signature validation could leave a valid sighash in the buffer, an invalid hash-type could be incorrectly accepted, which would create a consensus split between Zebra and zcashd nodes. This issue has been patched in zebrad version 4.4.0 and zebra-script version 6.0.0.

CVSS 4.0 · 9.3 Critical EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra-script Zebrad

CVE-2026-44500

ZEBRA: Allocation Amplification in Inbound Network Deserializers

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.4.0, prior to zebra-chain version 7.0.0, and prior to zebra-network version 6.0.0, several inbound deserialization paths in Zebra allocated buffers sized against generic transport or block-size ceilings before the tighter protocol or consensus limits were enforced. An unauthenticated or post-handshake peer could therefore force the node to preallocate and parse for orders of magnitude more data than the protocol intended, across headers messages, equihash solutions in block headers, Sapling spend vectors in V5/V4 transactions, and coinbase script bytes in blocks. This issue has been patched in zebrad version 4.4.0, zebra-chain version 7.0.0, and zebra-network version 6.0.0.

CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra-chain Zebra-network and 1 more

CVE-2026-41585

ZEBRA: Denial of Service via Interrupted JSON-RPC Requests from Authenticated Clients

ZEBRA is a Zcash node written entirely in Rust. From zebrad versions 2.2.0 to before 4.3.1 and from zebra-rpc versions 1.0.0-beta.45 to before 6.0.2, a vulnerability in Zebra's JSON-RPC HTTP middleware allows an authenticated RPC client to cause a Zebra node to crash by disconnecting before the request body is fully received. The node treats the failure to read the HTTP request body as an unrecoverable error and aborts the process instead of returning an error response. This issue has been patched in zebrad version 4.3.1 and zebra-rpc version 6.0.2.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed

Vendors

Zfnd

Products

Zebra-rpc Zebrad

CVE-2026-40880

Zebra: Cached Mempool Verification Bypasses Consensus Rules for Ahead-of-Tip Blocks

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.1 and zebra-consensus version 5.0.2, a logic error in Zebra's transaction verification cache could allow a malicious miner to induce a consensus split. By carefully submitting a transaction that is valid for height H+1 but invalid for H+2 and then mining that transaction in a block at height H+2, a miner could cause vulnerable Zebra nodes to accept an invalid block, leading to a consensus split from the rest of the Zcash network. This vulnerability is fixed in zebrad version 4.3.1 and zebra-consensus version 5.0.2.

CVSS 4.0 · 7.2 High EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra-consensus Zebrad Zebra-consensus and 1 more

CVE-2026-40881

Zebra: addr/addrv2 Deserialization Resource Exhaustion

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.0 and zebra-network version 5.0.1, when deserializing addr or addrv2 messages, which contain vectors of addresses, Zebra would fully deserialize them up to a maximum length (over 233,000) that was derived from the 2 MiB message size limit. This is much larger than the actual limit of 1,000 messages from the specification. Zebra would eventually check that limit but, at that point, the memory for the larger vector was already allocated. An attacker could cause out-of-memory aborts in Zebra by sending multiple such messages over different connections. This vulnerability is fixed in zebrad version 4.3.0 and zebra-network version 5.0.1.

CVSS 4.0 · 6.3 Medium EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra-network Zebrad Zebra-network and 1 more

CVE-2026-34202

Zebra node crash — V5 transaction hash panic (P2P reachable)

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.0 and zebra-chain version 6.0.1, a vulnerability in Zebra's transaction processing logic allows a remote, unauthenticated attacker to cause a Zebra node to panic (crash). This is triggered by sending a specially crafted V5 transaction that passes initial deserialization but fails during transaction ID calculation. This issue has been patched in zebrad version 4.3.0 and zebra-chain version 6.0.1.

CVSS 4.0 · 9.2 Critical EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra-chain Zebra and 1 more

CVE-2026-34377

Zebra has a Consensus Failure due to Improper Verification of V5 Transactions

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.0 and zebra-consensus version 5.0.1, a logic error in Zebra's transaction verification cache could allow a malicious miner to induce a consensus split. By matching a valid transaction's txid while providing invalid authorization data, a miner could cause vulnerable Zebra nodes to accept an invalid block, leading to a consensus split from the rest of the Zcash network. This would not allow invalid transactions to be accepted but could result in a consensus split between vulnerable Zebra nodes and invulnerable Zebra and Zcashd nodes. This issue has been patched in zebrad version 4.3.0 and zebra-consensus version 5.0.1.

CVSS 4.0 · 8.4 High EPSS < 1% KEV · Not listed

Vendors

Zcashfoundation Zfnd

Products

Zebra Zebra-consensus Zebra and 1 more