---
id: CVE-2026-52732
title: ZEBRA is a Zcash node written entirely in Rust
summary: >-
  ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, one
  unauthenticated P2P peer can monopolize all 25 MAX_INBOUND_CONCURRENCY slots
  in Zebra's inbound mempool download and verification pipeline. In
  zebrad/src/components/memp…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-770
vendor: zebrad
product: zebrad
affected:
  - zebrad <= 4.4.1
patched:
  - zebrad 4.5.0
published: '2026-08-18'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:13:25.910'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-52732'
references:
  - url: >-
      https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd
    label: security-advisories@github.com
  - url: 'https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0'
    label: security-advisories@github.com
  - url: >-
      https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-4fc2-h7jh-287c
    label: security-advisories@github.com
  - url: >-
      https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-4fc2-h7jh-287c
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://github.com/ZcashFoundation/zebra/blob/d4cd662c716382f6397d2a730148025a1ca79fec/zebrad/src/components/mempool/downloads.rs#L82
  - url: 'https://github.com/advisories/GHSA-4fc2-h7jh-287c'
tags:
  - nvd
  - ghsa
  - rust
epss: 0.00507
epssPercentile: 0.40712
ecosystem: rust
ingestedAt: '2026-07-02T19:41:50.908Z'
---

## Overview

ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, one unauthenticated P2P peer can monopolize all 25 MAX_INBOUND_CONCURRENCY slots in Zebra's inbound mempool download and verification pipeline. In zebrad/src/components/mempool/downloads.rs, the bounded queue was shared globally without per-peer accounting, while peer identity was not carried through Gossip and FullQueue responses were mapped to Response::Nil instead of reaching overload disconnection handling. An attacker can advertise fake transaction identifiers and remain silent so each task holds a slot until TRANSACTION_DOWNLOAD_TIMEOUT, then periodically refill the queue as slots expire. While saturated, honest peer transactions and local sendrawtransaction requests are rejected with MempoolError::FullQueue, although block validation and synchronization continue. This issue is fixed in version 4.5.0.

## Remediation

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

## Package advisory (CVE-2026-52732)

Affected packages:

- `zebrad <= 4.4.1`

Patched in:

- `zebrad 4.5.0`

Source: https://github.com/advisories/GHSA-4fc2-h7jh-287c