zebrad vulnerable to getblocks/getheaders locator CPU amplification via uncapped vector length

Exploitation

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

CVSS

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

EPSS

No dated EPSS signal available.

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. Summary The readgetblocks and readgetheaders codec paths accepted block locator vectors up to approximately 65,535 entries (the generic TrustedPreallocate ceiling derived from MAXPROTOCOLMESSAGELEN), rather than the protocol-specification limit of 101 entries (matching zcashd's MAXLOCATORSZ). Each entry in the locator vector triggers a per-hash chain lookup (HashMap::containskey + RocksDB::containshash) in findchainintersection on a tokio blocking-pool thread. A single maximally-sized getblocks message occupies one blocking-pool thread for approximately 10–65ms. Under sustained load from multiple peers, this can degrade state-read performance for block validation, RPC, and mempool lookups. Details The readheaders codec path already implements the correct pattern: it reads the CompactSize count, validates against MAXHEADERSPERMESSAGE = 160 before…

Published by the source

2 Jul 2026, 19:34 UTC

Last modified by the source

2 Jul 2026, 19:34 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-443g-gwgp-49x4

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# Patch Next advisory brief: GHSA-443g-gwgp-49x4

Advisory: zebrad vulnerable to getblocks/getheaders locator CPU amplification via uncapped vector length
IDs: GHSA-443g-gwgp-49x4
Record: https://patchnext.com/advisories/ghsa-443g-gwgp-49x4 (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: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: zebra-chain 8.0.0; zebrad 4.5.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io zebra-chain: affected < 8.0.0; fixed in 8.0.0
- crates.io zebrad: affected < 4.5.0; fixed in 4.5.0

## Suggested inspection (read-only)
- crates.io zebra-chain: 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-chain, 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-443g-gwgp-49x4 (GitHub-reviewed advisory GHSA-443g-gwgp-49x4 lists affected ranges: crates.io zebrad >=0 =0 <8.0.0)

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