CVE-2026-40880

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

HIGH
8.1
CVSS Score
Published: April 21, 2026 at 07:18 PM UTC
Updated: October 26, 2026 at 09:10 PM UTC
4 products affected across 2 vendorsZebradZebra ConsensusZebra Consensus

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Severity
HIGH8.1
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 5.0.2
v < 4.3.1
v < 5.0.2
Affected range stops below 5.0.2, so it looks safe — our inference, not a vendor statement
v < 4.3.1
Affected range stops below 4.3.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (1)

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-1025

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