CVE-2026-41583 (GCVE-0-2026-41583)

Vulnerability from cvelistv5 – Published: 2026-05-08 14:55 – Updated: 2026-05-08 19:42

Title

ZEBRA: Consensus Divergence in Transparent Sighash Hash-Type Handling

Summary

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.1 and prior to zebra-script version 5.0.2, after a refactoring, Zebra failed to validate a consensus rule that restricted the possible values of sighash hash types for V5 transactions which were enabled in the NU5 network upgrade. Zebra nodes could thus accept and eventually mine a block that would be considered invalid by zcashd nodes, creating a consensus split between Zebra and zcashd nodes. In a similar vein, for V4 transactions, Zebra mistakenly used the "canonical" hash type when computing the sighash while zcashd (correctly per the spec) uses the raw value, which could also crate a consensus split. This issue has been patched in zebrad version 4.3.1 and zebra-script version 5.0.2.

Severity

9.3 (Critical)


                        
                          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

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-05-08 19:42 UTC

CWE

CWE-573 - Improper Following of Specification by Caller

Assigner

GitHub_M mitre root

References

1 reference

URL	Tags
https://github.com/ZcashFoundation/zebra/security…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version	CPE status
ZcashFoundation	zebra	Affected: zebrad < 4.3.1 Affected: zebra-script < 5.0.2	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-41583

Vulnerability from fkie_nvd - Published: 2026-05-08 15:16 - Updated: 2026-06-17 10:46

Severity

9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-8m29-fpq5-89jj	Vendor Advisory

Impacted products

	Vendor	Product	Version
	zfnd	zebra-script	*
	zfnd	zebrad	*

JSON

To clipboard

{
  "affected": [
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      "affectedData": [
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          "product": "zebra",
          "vendor": "ZcashFoundation",
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        }
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    }
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}

GHSA-8M29-FPQ5-89JJ

Vulnerability from github – Published: 2026-04-18 01:15 – Updated: 2026-05-12 13:33

Summary

Zebra Vulnerable to Consensus Divergence in Transparent Sighash Hash-Type Handling

Details

CVE-2026-41583: Consensus Divergence in Transparent Sighash Hash-Type Handling

Summary

After a refactoring, Zebra failed to validate a consensus rule that restricted the possible values of sighash hash types for V5 transactions which were enabled in the NU5 network upgrade. Zebra nodes could thus accept and eventually mine a block that would be considered invalid by zcashd nodes, creating a consensus split between Zebra and zcashd nodes.

In a similar vein, for V4 transactions, Zebra mistakenly used the "canonical" hash type when computing the sighash while zcashd (correctly per the spec) uses the raw value, which could also crate a consensus split.

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 is currently alleviated by the fact that currently most miners run zcashd.

Affected Versions

All Zebra versions prior to version 4.3.1. (Some older versions are not impacted but are no longer supported by the network.)

Description

Verification of transparent transactions inherits the Bitcoin Script verification code in C++. Since it is consensus-critical, this code was called from Zebra through foreign function interface (FFI). That interface was clunky because it required parsing the whole transaction in C++ code, which would then pull Rust libraries which could get in conflict with Zebra code. A refactoring was done so that only the verification itself was done in C++, and the rest done by Rust code, using a callback. However, in this refactoring, it was not noticed that a particular consensus rule - only accepting known hash types in transparent transaction signatures - was being enforced in C++ code and thus had to be enforced by the Rust caller.

An attacker could exploit this by:

Submitting a V4 or V5 transaction with an invalid hash type
The V5 transaction would be accepted by Zebra nodes but not by zcashd nodes (and vice-versa for V4), creating a consensus split in the network.

Impact

Consensus Failure

Attack Vector: Network.
Effect: Network partition/consensus split.
Scope: Any Zebra affected Zebra node

Fixed Versions

This issue is fixed in Zebra 4.3.1.

The fix adds the consensus check in the caller of the C++ verification code. It also uses the raw hash type for V4 sighash computations.

Mitigation

Users should upgrade to Zebra 4.3.1 or later immediately.

There are no known workarounds for this issue. Immediate upgrade is the only way to ensure the node remains on the correct consensus path and is protected against malicious chain forks.

Credits

Thanks Alex “Scalar” Sol for finding and reporting the issue, and to @sangsoo-osec who independently found the same issue and demonstrated that the V4 variant was also exploitable.

Severity

9.1 (Critical)


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

9.3 (Critical)


                  
                    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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "zebrad"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.3.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "zebra-script"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.0.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-41583"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-573"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-18T01:15:24Z",
    "nvd_published_at": "2026-05-08T15:16:41Z",
    "severity": "CRITICAL"
  },
  "details": "# CVE-2026-41583: Consensus Divergence in Transparent Sighash Hash-Type Handling\n\n## Summary\n\nAfter a refactoring, Zebra failed to validate a consensus rule that restricted the possible values of sighash hash types for V5 transactions which were enabled in the NU5 network upgrade. Zebra nodes could thus accept and eventually mine a block that would be considered invalid by zcashd nodes, creating a consensus split between Zebra and zcashd nodes.\n\nIn a similar vein, for V4 transactions, Zebra mistakenly used the \"canonical\" hash type when computing the sighash while zcashd (correctly per the spec) uses the raw value, which could also crate a consensus split.\n\n## Severity\n\n**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.\n\nNote that the impact is currently alleviated by the fact that currently most miners run `zcashd`.\n\n## Affected Versions\n\nAll Zebra versions prior to version 4.3.1. (Some older versions are not impacted but are no longer supported by the network.)\n\n## Description\n\nVerification of transparent transactions inherits the Bitcoin Script verification code in C++. Since it is consensus-critical, this code was called from Zebra through foreign function interface (FFI). That interface was clunky because it required parsing the whole transaction in C++ code, which would then pull Rust libraries which could get in conflict with Zebra code. A refactoring was done so that only the verification itself was done in C++, and the rest done by Rust code, using a callback. However, in this refactoring, it was not noticed that a particular consensus rule - only accepting known hash types in transparent transaction signatures - was being enforced in C++ code and thus had to be enforced by the Rust caller.\n\nAn attacker could exploit this by:\n\n- Submitting a V4 or V5 transaction with an invalid hash type\n- The V5 transaction would be accepted by Zebra nodes but not by `zcashd` nodes (and vice-versa for V4), creating a consensus split in the network.\n\n## Impact\n\n**Consensus Failure**\n\n- **Attack Vector:** Network.\n- **Effect:** Network partition/consensus split.\n- **Scope:** Any Zebra affected Zebra node\n\n## Fixed Versions\n\nThis issue is fixed in Zebra 4.3.1.\n\nThe fix adds the consensus check in the caller of the C++ verification code. It also uses the raw hash type for V4 sighash computations.\n\n## Mitigation\n\nUsers should upgrade to Zebra 4.3.1 or later immediately.\n\nThere are no known workarounds for this issue. Immediate upgrade is the only way to ensure the node remains on the correct consensus path and is protected against malicious chain forks.\n\n## Credits\n\nThanks Alex \u201cScalar\u201d Sol for finding and reporting the issue, and to @sangsoo-osec who independently found the same issue and demonstrated that the V4 variant was also exploitable.",
  "id": "GHSA-8m29-fpq5-89jj",
  "modified": "2026-05-12T13:33:05Z",
  "published": "2026-04-18T01:15:24Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-8m29-fpq5-89jj"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41583"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ZcashFoundation/zebra/commit/1f605eca5c55e3b65229fa01a97d9aa84fd37447"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ZcashFoundation/zebra"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Zebra Vulnerable to Consensus Divergence in Transparent Sighash Hash-Type Handling"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Action not permitted

CVE-2026-41583 (GCVE-0-2026-41583)

FKIE_CVE-2026-41583

GHSA-8M29-FPQ5-89JJ

CVE-2026-41583: Consensus Divergence in Transparent Sighash Hash-Type Handling

Summary

Severity

Affected Versions

Description

Impact

Fixed Versions

Mitigation

Credits

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