Zebra v4.4.0 still accepts V5 SIGHASH_SINGLE without a corresponding output

Exploitation

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

CVSS 4.0

9.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:H · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Consensus Divergence in V5 Transparent SIGHASHSINGLE With No Corresponding Output Summary Zebra failed to enforce a ZIP-244 consensus rule for V5 transparent transactions: when an input is signed with SIGHASHSINGLE and there is no transparent output at the same index as that input, validation must fail. Zebra instead asked the underlying sighash library to compute a digest, and that library produced a digest over an empty output set rather than failing. An attacker could craft a V5 transaction with more transparent inputs than outputs that Zebra accepts but zcashd rejects, creating a consensus split between Zebra and zcashd nodes. A previous fix (GHSA-cwfq-rfcr-8hmp) addressed a closely related case in the same area of the code, but did not cover this specific one. Severity Critical - This is a Consensus Vulnerability that could allow a malicious party to induce network partitioning, service disruption, and potential double-spend attacks against affected nodes. Note that the impact…

Published by the source

8 May 2026, 18:27 UTC

Last modified by the source

8 May 2026, 18:27 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-pvmv-cwg8-v6c8

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# Patch Next advisory brief: GHSA-pvmv-cwg8-v6c8

Advisory: Zebra v4.4.0 still accepts V5 SIGHASH_SINGLE without a corresponding output
IDs: GHSA-pvmv-cwg8-v6c8
Record: https://patchnext.com/advisories/ghsa-pvmv-cwg8-v6c8 (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: Critical (CVSS 9.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: zebra-script 6.0.1; zebrad 4.4.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io zebra-script: affected < 6.0.1; fixed in 6.0.1
- crates.io zebrad: affected < 4.4.1; fixed in 4.4.1

## Suggested inspection (read-only)
- crates.io zebra-script: 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-script, 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-pvmv-cwg8-v6c8 (GitHub-reviewed advisory GHSA-pvmv-cwg8-v6c8 lists affected ranges: crates.io zebrad >=0 =0 <6.0.1)

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