Description

Stack-based buffer overflow in Windows Installer allows an authorized attacker to elevate privileges locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.8",
  "pubDate": "2026-08-11T17:19:12.150Z",
  "pubdate": "2026-08-11T17:19:12.150Z",
  "executiveSummary": "A stack-based buffer overflow vulnerability exists within Windows Installer, posing significant risk to local system security. The vulnerability allows an authenticated local attacker to execute arbitrary code and achieve local elevation of privileges on affected systems.\nThe flaw resides in how Windows Installer processes specific installation parameters or data structures, leading to memory corruption when input bounds are improperly validated. Successful exploitation compromises the integrity and confidentiality of the host operating system by granting the attacker elevated execution privileges, typically matching those of the SYSTEM context under which the installer service often operates.\nThe risk implication is critical for multi-tenant environments or workstations where low-privileged users possess interactive or programmatic access. Exploitation requires local access to the target machine and that the attacker is already authorized to interact with the local installation subsystem.\nMitigation requires applying vendor-supplied security updates as soon as they become available, alongside implementing strict monitoring of installer execution behaviors and enforcing principle of least privilege for local user accounts.",
  "technicalDetails": "The vulnerability is a classic stack-based buffer overflow occurring within the Windows Installer service component. The root cause stems from insufficient boundary checks when the application copies untrusted input into a fixed-size memory buffer on the stack. When an authorized local attacker supplies a specially crafted payload or parameter to the installer subsystem, the input exceeds the allocated buffer dimensions, resulting in the overwriting of adjacent stack memory, including saved frame pointers and return addresses.\nThe attack flow requires the adversary to possess local execution capabilities and authorization to initiate or interact with Windows Installer processes. The exploitation method involves supplying malformed data via command-line arguments, custom action payloads, or manipulated installation packages (such as .msi files) processed by the vulnerable component. Upon parsing the malicious input, the bounds checking failure triggers the overflow condition.\nDuring execution, the overwritten return address redirects the control flow of the affected process to attacker-supplied shellcode or existing memory gadgets, facilitating arbitrary code execution. Because Windows Installer frequently runs with high privileges, such as NT AUTHORITY\\SYSTEM, successfully redirecting execution flow allows the attacker to inherit these elevated privileges, effectively bypassing standard operating system access controls.\nThe vulnerability is exposed locally with no remote network attack vector required. Prerequisites for successful exploitation include local authentication and sufficient permissions to execute installation routines or trigger the vulnerable subsystem. Post-exploitation impact encompasses full system compromise, installation of persistent backdoors, creation of privileged accounts, and unauthorized access to sensitive system resources."
}