zebrad has full node denial of service via non-ASCII LongPollId in getblocktemplate

Exploitation

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

CVSS

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

EPSS

• CVE-2026-52731: 0.53% estimated exploitation activity in the next 30 days; percentile 44.90 (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 zebrad.toml sets rpc.listenaddr to a TCP address (RPC server is enabled). 3. An attacker can authenticate to the RPC endpoint. With the default enablecookieauth = true, this requires the attacker to read the .cookie file. With enablecookieauth = false, any network client reaching the RPC port can trigger it. Summary The getblocktemplate RPC handler panics when parsing a LongPollId parameter that contains non-ASCII (multi-byte UTF-8) characters. The handler performs byte-index string slicing on the user-supplied string, which panics in Rust when a byte index falls within a multi-byte character boundary. Because Zebra's release profile sets panic = "abort", the panic terminates the entire node process. Details The getblocktemplate handler receives a user-supplied LongPollId string and slices it at fixed byte offsets to extract the encoded tip hash and tip height. When the string contains multi-byte…

Published by the source

2 Jul 2026, 19:28 UTC

Last modified by the source

2 Jul 2026, 19:28 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-qv2r-v3mx-f4pf

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# Patch Next advisory brief: CVE-2026-52731

Advisory: zebrad has full node denial of service via non-ASCII LongPollId in getblocktemplate
IDs: CVE-2026-52731, GHSA-qv2r-v3mx-f4pf
Record: https://patchnext.com/advisories/cve-2026-52731 (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 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: zebra-rpc 8.0.0; zebrad 4.5.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io zebra-rpc: affected <= 7.0.0; fixed in 8.0.0
- crates.io zebrad: affected <= 4.4.1; fixed in 4.5.0

## Suggested inspection (read-only)
- crates.io zebra-rpc: check the installed version with your package manager.
- 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 zebra-rpc, 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-qv2r-v3mx-f4pf (GitHub-reviewed advisory GHSA-qv2r-v3mx-f4pf lists affected ranges: crates.io zebra-rpc >=0 =0 <=4.4.1)

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