---
id: CVE-2026-104436
title: >-
  Zebra before 4.5.0 contains an uncontrolled resource consumption vulnerability
  that allows remote P2P peers to exhaust blocking-pool threads by sending
  oversized block locator vectors
summary: >-
  Zebra before 4.5.0 contains an uncontrolled resource consumption vulnerability
  that allows remote P2P peers to exhaust blocking-pool threads by sending
  oversized block locator vectors. Attackers can send getblocks or getheaders
  messages …
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-770
vendor: ZcashFoundation
product: zebra
affected:
  - zebra < 4.5.0
  - zebra < 8.0.0
published: '2026-10-02'
updated: '2026-10-02'
sourceUpdated: '2026-10-02T12:17:14.210'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-104436'
references:
  - url: >-
      https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-443g-gwgp-49x4
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/zebra-before-4.5.0-cpu-amplification-via-uncapped-getblocks-getheaders-locator-length
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-02T12:17:44.335Z'
---

## Overview

Zebra before 4.5.0 contains an uncontrolled resource consumption vulnerability that allows remote P2P peers to exhaust blocking-pool threads by sending oversized block locator vectors. Attackers can send getblocks or getheaders messages with up to 65,535 locator hashes, triggering per-hash chain lookups that degrade block validation, RPC, and mempool performance.

## Remediation

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