---
id: CVE-2026-104423
title: >-
  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
summary: >-
  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 sha…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-405
vendor: ZcashFoundation
product: zebra
affected:
  - zebra < 6.2.1
published: '2026-10-02'
updated: '2026-10-02'
sourceUpdated: '2026-10-02T12:17:12.433'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-104423'
references:
  - url: >-
      https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-2p4c-3q4q-p463
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/zebra-before-6.2.1-denial-of-service-via-uncapped-v6-shielded-proof-verification
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-02T12:17:44.330Z'
---

## Overview

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.

## Remediation

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