CVE-2026-34377

# PoC for CVE-2026-34377: ZEBRA Consensus Split # This is a conceptual demonstration of the logic flaw. import hashlib def craft_malicious_tx(valid_tx): # In a real scenario, the attacker modifies the authorization data (e.g., signature) # such that the txid remains the same (SIGHASH_SINGLE/ANYONECANPAY abuse or malleability) # while the signature becomes invalid. # 1. Extract valid txid txid = valid_tx['txid'] # 2. Create a copy with modified authorization malicious_tx = valid_tx.copy() malicious_tx['authorization'] = "INVALID_SIGNATURE_DATA" # 3. The logic flaw implies the cache check passes based on txid # bypassing full verification on the block acceptance path. print(f"[+] Crafted malicious tx with txid: {txid}") print(f"[+] Authorization: {malicious_tx['authorization']}") return malicious_tx # Simulate usage target_tx = {"txid": "abc123...", "authorization": "VALID_SIG"} print(craft_malicious_tx(target_tx))

{"cve": {"id": "CVE-2026-34377", "sourceIdentifier": "[email protected]", "published": "2026-03-31T15:16:19.233", "lastModified": "2026-04-06T16:57:21.713", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.0 and zebra-consensus version 5.0.1, a logic error in Zebra's transaction verification cache could allow a malicious miner to induce a consensus split. By matching a valid transaction's txid while providing invalid authorization data, a miner could cause vulnerable Zebra nodes to accept an invalid block, leading to a consensus split from the rest of the Zcash network. This would not allow invalid transactions to be accepted but could result in a consensus split between vulnerable Zebra nodes and invulnerable Zebra and Zcashd nodes. This issue has been patched in zebrad version 4.3.0 and zebra-consensus version 5.0.1."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/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": 8.4, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "HIGH", "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:L/UI:N/S:U/C:N/I:H/A:H", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-347"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:zfnd:zebra:*:*:*:*:*:rust:*:*", "versionEndExcluding": "4.3.0", "matchCriteriaId": "4B93957D-63A6-4232-8046-FDF593752C05"}, {"vulnerable": true, "criteria": "cpe:2.3:a:zfnd:zebra-consensus:*:*:*:*:*:rust:*:*", "versionEndExcluding": "5.0.1", "matchCriteriaId": "D958D1C3-B1F2-48EE-A41C-777DE3C0A8B1"}]}]}], "references": [{"url": "https://github.com/ZcashFoundation/zebra/releases/tag/v4.3.0", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-3vmh-33xr-9cqh", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://zfnd.org/zebra-4-3-0-critical-security-fixes-zip-235-support-and-performance-improvements", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}