---
id: "CVE-2026-123557"
page: "https://infrastack.ai/live/CVE-2026-123557"
kind: "vulnerability"
aliases: ["CVE-2026-123557"]
title: "Zebra zebrad: remote peers can crash syncing nodes via race condition"
severity: "high"
cvss: 8.2
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["package", "self-hosted", "zcash", "zebra", "zebrad"]
not_affected_if: ["not-syncing", "zebrad-7.0.0-or-later"]
published_at: "2026-11-08T02:16:47+00:00"
first_seen_at: "2026-11-08T02:21:11+00:00"
updated_at: "2026-11-08T02:23:19+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123557", "first_seen_at": "2026-11-08T02:21:11+00:00"}]
exploit_sources: []
---

# Zebra zebrad: remote peers can crash syncing nodes via race condition

Link for people: https://infrastack.ai/live/CVE-2026-123557 (this .md is for agents)

Zebra's zebrad node before 7.0.0 has a reachable assertion race condition. An unauthenticated remote peer can make a syncing node abort by sending empty FindBlocks or FindHeaders replies and stopping reads on its socket.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed zebrad version (`zebrad --version`) and compare it with the fixed version in the product ranges; versions before `7.0.0` are affected.
- Confirm whether the node is syncing and reachable from peers on the network.

## Fix

- Upgrade zebrad to `7.0.0` or later.

## Timeline

- 2026-11-08T02:21:11+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123557

## Documents

- [advisory] Vendor advisory: github.com https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-6v36-c42v-v98p
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/zebra-zebrad-before-7.0.0-reachable-assertion-dos-via-peer-disconnection

## From the sources

ZcashFoundation Zebra zebrad before 7.0.0 contains a reachable assertion race condition that allows unauthenticated remote peers to abort the node by triggering disconnection during a blocked outbound send. Malicious peers can return empty FindBlocks or FindHeaders replies and stop reading their socket, dropping an unresolved MustUseClientResponseSender and terminating syncing nodes.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_