CVE-2026-65774
Summary
by MITRE • 08/11/2026
Heap-based buffer overflow in Windows Installer allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability represents a critical heap-based buffer overflow within the Windows Installer component that enables local privilege escalation for authenticated attackers. The flaw exists in how the installer processes certain input data structures, specifically when handling malformed or oversized payload elements during installation operations. Attackers with legitimate user accounts can exploit this weakness by crafting malicious installation packages or manipulating existing installation processes to trigger the buffer overflow condition.
The technical implementation of this vulnerability stems from inadequate bounds checking within the heap memory allocation routines used by Windows Installer. When processing certain installation parameters, the system fails to validate input lengths against allocated buffer sizes, creating opportunities for data to overwrite adjacent memory regions. This memory corruption can be leveraged to overwrite critical function pointers or return addresses, ultimately allowing attackers to execute arbitrary code with elevated privileges. The vulnerability is classified under cwe-121 heap-based buffer overflow and aligns with attack techniques described in the mitre att&ck framework under privilege escalation tactics.
The operational impact of this vulnerability extends beyond simple local exploitation as it provides attackers with a reliable path to gain system-level access on compromised machines. Once successfully exploited, the attacker can execute code with kernel-level privileges, potentially enabling full system compromise, data exfiltration, or establishment of persistent backdoors. The attack vector typically involves creating or modifying installation packages that trigger the vulnerable code path during normal installation procedures, making detection challenging as legitimate administrative activities may appear normal to security monitoring systems.
Mitigation strategies should focus on immediate patching of affected windows installer components through official microsoft security updates. Organizations must implement comprehensive patch management processes to ensure timely deployment of security fixes across all system environments. Additional defensive measures include restricting user privileges during installation processes, implementing application whitelisting controls, and monitoring for unusual installation activities or privilege escalation attempts. Network segmentation and principle of least privilege access controls can further limit the potential impact should exploitation occur. The vulnerability demonstrates the critical importance of maintaining up-to-date system components and highlights the need for robust memory safety practices in system-level software components that handle untrusted input data.