zebrad has mempool transaction admission denial via single-peer inbound queue saturation

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-52732: 0.51% estimated exploitation activity in the next 30 days; percentile 43.30 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Am I affected You are affected if: 1. You run zebrad up to and including v4.4.1. 2. Your node accepts inbound P2P connections (network.listenaddr is set, which is the default). 3. Your node's mempool is active (node is synced near the chain tip). All default configurations are affected. Summary A single unauthenticated P2P peer can monopolize all 25 inbound mempool download/verification slots (MAXINBOUNDCONCURRENCY) by advertising fake transaction IDs. While the slots are occupied, all other inbound transactions from honest peers and local RPC sendrawtransaction calls are rejected with MempoolError::FullQueue. The attacker peer is never scored for misbehavior and is not disconnected, allowing sustained denial of mempool admission. Details The mempool download/verification pipeline at zebrad/src/components/mempool/downloads.rs uses a single bounded pool of 25 concurrent tasks. Three architectural gaps combine to produce the vulnerability: 1. No per-peer accounting: the 25 slots are…

Published by the source

2 Jul 2026, 19:39 UTC

Last modified by the source

2 Jul 2026, 19:39 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-4fc2-h7jh-287c

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# Patch Next advisory brief: CVE-2026-52732

Advisory: zebrad has mempool transaction admission denial via single-peer inbound queue saturation
IDs: CVE-2026-52732, GHSA-4fc2-h7jh-287c
Record: https://patchnext.com/advisories/cve-2026-52732 (revision 1, source checked 26 Oct 2026, 15:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: zebrad 4.5.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io zebrad: affected <= 4.4.1; fixed in 4.5.0

## Suggested inspection (read-only)
- crates.io zebrad: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on zebrad.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4fc2-h7jh-287c (GitHub-reviewed advisory GHSA-4fc2-h7jh-287c lists affected ranges: crates.io zebrad >=0 <=4.4.1)

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