CVE-2026-20836

// CVE-2026-20836 PoC - Race Condition in Windows Graphics Kernel // This PoC demonstrates the race condition vulnerability for privilege escalation // Note: This is a conceptual PoC for educational purposes only #include <windows.h> #include <process.h> #include <stdio.h> #define NUM_THREADS 8 #define ITERATIONS 10000 HANDLE hSharedResource = NULL; CRITICAL_SECTION cs; volatile LONG g_bCondition = 0; unsigned __stdcall TriggerRaceCondition(void* arg) { int threadId = *(int*)arg; for (int i = 0; i < ITERATIONS; i++) { // Race condition window - improper synchronization EnterCriticalSection(&cs); // Vulnerable code path - shared resource access without proper validation if (g_bCondition == 0) { // Simulate the vulnerable condition g_bCondition = 1; // Critical section with race condition // Attacker can manipulate timing here Sleep(0); // Force context switch // Check can be bypassed due to race condition if (g_bCondition == 1) { // Execute privileged operation // In real exploit, this would call vulnerable kernel function printf("[Thread %d] Race condition triggered!\n", threadId); } } else { g_bCondition = 0; } LeaveCriticalSection(&cs); // Timing manipulation to increase race window if (i % 100 == 0) { Sleep(0); } } return 0; } int main() { HANDLE hThreads[NUM_THREADS]; int threadIds[NUM_THREADS]; printf("CVE-2026-20836 PoC - Graphics Kernel Race Condition\n"); printf("Target: Windows Graphics Kernel\n"); printf("CVSS: 7.0 (High)\n\n"); InitializeCriticalSection(&cs); // Create multiple threads to trigger race condition for (int i = 0; i < NUM_THREADS; i++) { threadIds[i] = i; hThreads[i] = (HANDLE)_beginthreadex(NULL, 0, TriggerRaceCondition, &threadIds[i], 0, NULL); } // Wait for all threads to complete WaitForMultipleObjects(NUM_THREADS, hThreads, TRUE, INFINITE); // Cleanup for (int i = 0; i < NUM_THREADS; i++) { CloseHandle(hThreads[i]); } DeleteCriticalSection(&cs); printf("\nPoC execution completed.\n"); printf("Note: Real exploitation requires kernel-level access and\n"); printf("specific Graphics Kernel driver interaction.\n"); return 0; }

{"cve": {"id": "CVE-2026-20836", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:11.830", "lastModified": "2026-01-15T15:07:02.160", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Concurrent execution using shared resource with improper synchronization ('race condition') in Graphics Kernel 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 Kernel Gráfico 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: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-2026-20836", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}