---
id: CVE-2026-123555
title: >-
  Zebra 2.3.0 before 7.0.0 Denial of Service via Unscored Script Verification
  Failures
summary: >-
  Zebra from 2.3.0 before 7.0.0 contains a denial of service vulnerability that
  allows unauthenticated peers to evade misbehavior scoring by sending
  transactions or blocks with invalid transparent scripts. Attackers can flood
  mempool with …
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'
cvssSource: cna
cwe:
  - CWE-755
vendor: ZcashFoundation
product: zebra
affected:
  - zebra >= 2.3.0 < 7.0.0
  - zebra >= 1.0.0-beta.46 < 18.0.0
published: '2026-11-08'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T01:37:57.593Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-123555'
references:
  - url: >-
      https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-jq45-ghw5-v37x
    label: GitHub Security Advisory (GHSA-jq45-ghw5-v37x)
  - url: >-
      https://github.com/ZcashFoundation/zebra/commit/e8db87eb69254e0d4eedd058eadd48bdfa09065a
    label: Patch Commit
  - url: >-
      https://www.vulncheck.com/advisories/zebra-2.3.0-before-7.0.0-denial-of-service-via-unscored-script-verification-failures
    label: >-
      VulnCheck Advisory: Zebra 2.3.0 before 7.0.0 Denial of Service via
      Unscored Script Verification Failures
tags:
  - cve.org
ingestedAt: '2026-11-08T02:43:18.667Z'
---

## Overview

Zebra from 2.3.0 before 7.0.0 contains a denial of service vulnerability that allows unauthenticated peers to evade misbehavior scoring by sending transactions or blocks with invalid transparent scripts. Attackers can flood mempool with script-failing transactions or serve forged v5 block bodies with altered scriptSig bytes to exhaust CPU and repeatedly stall block sync.

## Affected

- `zebra >= 2.3.0 < 7.0.0`
- `zebra >= 1.0.0-beta.46 < 18.0.0`

## Remediation

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