CVE-2026-52732
Received Received - Intake

Denial of Service in ZEBRA Node

Publication date: 2026-08-18

Last updated on: 2026-08-18

Assigner: GitHub, Inc.

Description
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.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-08-18
Last Modified
2026-08-18
Generated
2026-08-19
AI Q&A
2026-08-18
EPSS Evaluated
N/A
NVD
CVE-2026-52732
EUVD
EUVD-2026-61170

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
zebra zebra 4.5.0
zcashfoundation zebra 4.5.0
zcashfoundation zebra to 4.4.1 (inc)

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-770 The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

CVE-2026-52732 is a denial-of-service vulnerability in Zebra, a Zcash node implementation. It allows one unauthenticated peer to monopolize all 25 mempool slots by advertising fake transactions, preventing legitimate transactions from being processed. The attack exploits lack of per-peer accounting and proper overload handling.

Detection Guidance

Monitor for high mempool queue usage or repeated FullQueue errors in Zebra logs. Check for excessive inbound connections from a single peer or unusual transaction advertisement patterns. Use Zebra's built-in metrics or logging to track slot occupancy and peer behavior.

Impact Analysis

If exploited, this vulnerability can cause your Zebra node to reject legitimate transactions from honest peers and local RPC requests with MempoolError::FullQueue. Block validation and synchronization remain unaffected. The attack requires minimal resources (~1 KB/s bandwidth) and stops affecting your node once the malicious peer disconnects.

Mitigation Strategies

Upgrade Zebra to version 4.5.0 or later to apply the fix. If upgrading is not immediately possible, restrict inbound peer connections or implement network-level rate limiting to reduce the attack surface. Monitor mempool performance and peer activity closely.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-52732. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart