CVE-2026-70346
Summary
by MITRE • 08/11/2026
Stack-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
A stack-based buffer overflow vulnerability exists within the Windows Installer component that enables a locally authenticated attacker to escalate their privileges from standard user level to system level execution. This flaw resides in the installer's handling of malformed input data during package installation processes, specifically when processing certain parameters or configuration values. The vulnerability stems from insufficient bounds checking on stack allocated buffers, allowing an attacker to overwrite adjacent memory locations including return addresses and control data structures. When an authenticated user executes a specially crafted installer package or triggers the vulnerable code path through legitimate installation operations, the overflow can be exploited to redirect execution flow and gain elevated privileges.
The technical implementation of this vulnerability aligns with common software security weaknesses categorized under CWE-121 stack-based buffer overflow conditions. The flaw typically manifests when Windows Installer processes untrusted input from installer packages or configuration files without proper validation mechanisms. Attackers can leverage this vulnerability by crafting malicious installation packages that contain oversized data payloads designed to overwrite the stack frame of the executing installer process. This manipulation enables execution of arbitrary code with system-level privileges, bypassing standard user access controls and security boundaries.
Operationally, this vulnerability presents significant risk to organizations as it requires only local authentication to exploit, making it accessible through various attack vectors including social engineering campaigns or compromised user accounts. The privilege escalation capability allows attackers to bypass traditional endpoint protection measures and gain unrestricted access to system resources, potentially enabling data exfiltration, persistence establishment, or further network lateral movement. Systems running affected versions of Windows Installer are particularly vulnerable when users execute third-party installation packages or when administrators deploy software with insufficient input validation.
Mitigation strategies for this vulnerability include immediate deployment of Microsoft security updates that address the specific buffer overflow condition within Windows Installer components. Organizations should implement application whitelisting policies to restrict execution of unauthorized installer packages and enable automatic update mechanisms for all Windows systems. Network segmentation and privilege separation practices can limit the impact if exploitation occurs, while regular security assessments should verify proper input validation in installation processes. Additionally, implementing monitoring solutions to detect suspicious installation activities or unusual privilege escalation events provides early warning capabilities. The exploitability of this vulnerability aligns with ATT&CK technique T1068 for local privilege escalation and T1547 for registry modification, making it a critical target for comprehensive defensive measures.