---
id: "CVE-2026-123560"
page: "https://infrastack.ai/live/CVE-2026-123560"
kind: "vulnerability"
aliases: ["CVE-2026-123560"]
title: "Zebra: forged checkpoint block stalls initial sync until node restart"
severity: "high"
cvss: 8.7
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["package", "self-hosted", "zcash", "zebra"]
not_affected_if: ["already-synced-node", "version-7-or-later"]
published_at: "2026-11-08T02:16:48+00:00"
first_seen_at: "2026-11-08T02:21:11+00:00"
updated_at: "2026-11-08T02:23:06+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123560", "first_seen_at": "2026-11-08T02:21:11+00:00"}]
exploit_sources: []
---

# Zebra: forged checkpoint block stalls initial sync until node restart

Link for people: https://infrastack.ai/live/CVE-2026-123560 (this .md is for agents)

Zebra, a Zcash node implementation, leaves rejected block hashes in its sent-hash set when it receives a forged checkpoint block body. The node then stops requesting blocks, so an unauthenticated peer can stall initial sync until the node is restarted.

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

## How to check

- Check the installed Zebra version (`zebrad --version`) and compare it with the fixed version below.
- Look for a stalled initial sync in the node logs: no block height progress for an extended period.

## Fix

- Zebra: move to `7.0.0` or later.

## Timeline

- 2026-11-08T02:21:11+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123560

## Documents

- [advisory] Vendor advisory: github.com https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-9hq5-pfgc-cx5h
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/zebra-before-7.0.0-sync-denial-of-service-via-forged-checkpoint-block-body

## From the sources

Zebra before 7.0.0 contains an incomplete cleanup vulnerability that allows unauthenticated peers to stall initial sync by serving a forged checkpoint block body. Attackers can supply a body with forged authorizing data near the final checkpoint, leaving rejected hashes in the sent-hash set so the node stops requesting blocks until restart.

---

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