CVE-2026-104437: Improper Verification of Cryptographic Signature in ZcashFoundation zebra
Zebra before 4.4.0 contains a consensus divergence vulnerability in V5 transparent signature verification, computing a ZIP-244 digest for SIGHASH_SINGLE inputs lacking corresponding outputs instead of failing. Attackers can craft V5 transactions with fewer outputs than inputs that Zebra accepts and templates via getblocktemplate, producing blocks zcashd rejects.
AI Analysis
Technical Summary
CVE-2026-104437 describes a vulnerability in Zebra prior to version 4.4.0 where the software improperly verifies cryptographic signatures for V5 transparent transactions. The issue arises because Zebra computes a ZIP-244 digest for SIGHASH_SINGLE inputs missing corresponding outputs instead of failing as expected. This flaw can cause consensus divergence because Zebra accepts and templates certain malformed transactions that zcashd rejects, potentially leading to blockchain forks or inconsistencies.
Potential Impact
The vulnerability can lead to consensus divergence between Zebra nodes and zcashd nodes, undermining blockchain consistency and reliability. Attackers can exploit this by crafting V5 transactions with fewer outputs than inputs, which Zebra accepts but zcashd rejects, potentially causing Zebra nodes to build blocks that are invalid in the broader network context.
Mitigation Recommendations
Users should upgrade Zebra to version 4.4.0 or later where this vulnerability is fixed. Since the affected versions are explicitly prior to 4.4.0, applying the official fix by upgrading is the recommended remediation.
CVE-2026-104437: Improper Verification of Cryptographic Signature in ZcashFoundation zebra
Description
Zebra before 4.4.0 contains a consensus divergence vulnerability in V5 transparent signature verification, computing a ZIP-244 digest for SIGHASH_SINGLE inputs lacking corresponding outputs instead of failing. Attackers can craft V5 transactions with fewer outputs than inputs that Zebra accepts and templates via getblocktemplate, producing blocks zcashd rejects.
CVSS v4.0
Score 8.3high
Affected software
ZcashFoundation
zebra
pkg:github/zcashfoundation/zebraRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-104437 describes a vulnerability in Zebra prior to version 4.4.0 where the software improperly verifies cryptographic signatures for V5 transparent transactions. The issue arises because Zebra computes a ZIP-244 digest for SIGHASH_SINGLE inputs missing corresponding outputs instead of failing as expected. This flaw can cause consensus divergence because Zebra accepts and templates certain malformed transactions that zcashd rejects, potentially leading to blockchain forks or inconsistencies.
Potential Impact
The vulnerability can lead to consensus divergence between Zebra nodes and zcashd nodes, undermining blockchain consistency and reliability. Attackers can exploit this by crafting V5 transactions with fewer outputs than inputs, which Zebra accepts but zcashd rejects, potentially causing Zebra nodes to build blocks that are invalid in the broader network context.
Mitigation Recommendations
Users should upgrade Zebra to version 4.4.0 or later where this vulnerability is fixed. Since the affected versions are explicitly prior to 4.4.0, applying the official fix by upgrading is the recommended remediation.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-10-02T00:50:26.604Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6abf99b0a43b0b3b89b2694a
Added to database: 10/02/2026, 11:46:56 UTC
Last enriched: 10/02/2026, 12:01:32 UTC
Last updated: 10/03/2026, 03:06:13 UTC
Views: 13
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