ZEBRA: Mempool transaction admission denial via single-peer inbound queue saturation

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-52732
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-18 20:17:16 UTC
Updated2026-08-18 20:17:16 UTC
DescriptionZEBRA 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.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Problem Types: CWE-770 | CWE-770 CWE-770: Allocation of Resources Without Limits or Throttling

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA ZcashFoundation Zebra affected < 4.5.0 Not specified

References

ReferenceSourceLinkTags
github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557... [email protected] github.com
github.com/ZcashFoundation/zebra/releases/tag/v4.5.0 [email protected] github.com
github.com/ZcashFoundation/zebra/security/advisories/GHSA-4fc2-h7jh-287c 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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