---
id: CVE-2026-104424
title: >-
  Zebra before 6.1.0 contains an incorrect calculation vulnerability in its
  ZIP-317 block template selector that omits header and transaction-count size
  from the block budget
summary: >-
  Zebra before 6.1.0 contains an incorrect calculation vulnerability in its
  ZIP-317 block template selector that omits header and transaction-count size
  from the block budget. Attackers can place valid selectable transactions in a
  victim m…
severity: low
cvss: 3.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-131
vendor: ZcashFoundation
product: zebra
affected:
  - zebra < 6.1.0
published: '2026-10-02'
updated: '2026-10-02'
sourceUpdated: '2026-10-02T12:17:12.580'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-104424'
references:
  - url: >-
      https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-95m2-vx53-v2jw
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/zebra-before-6.1.0-incorrect-block-size-calculation-in-getblocktemplate
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-02T12:17:44.330Z'
---

## Overview

Zebra before 6.1.0 contains an incorrect calculation vulnerability in its ZIP-317 block template selector that omits header and transaction-count size from the block budget. Attackers can place valid selectable transactions in a victim miner's mempool to shape templates into oversized blocks, causing rejection and wasted proof-of-work.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.