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": "2026-08-11T17:19:11.780Z",
  "pubdate": "2026-08-11T17:19:11.780Z",
  "executiveSummary": "A stack-based buffer overflow vulnerability resides within Windows Installer, posing significant security risks to affected systems. This flaw enables an authorized local attacker to execute arbitrary code and achieve local privilege elevation, potentially leading to full compromise of the underlying operating system. The vulnerability affects the Windows Installer component across supported environments where the application processes maliciously crafted installation routines or parameters. Exploitation of this security defect requires the adversary to possess local execution capabilities and authorization to interact with the targeted installation service, restricting remote exploitability vectors. Successful exploitation compromises the confidentiality, integrity, and availability of the host by granting the attacker elevated operating system privileges, often corresponding to SYSTEM-level access depending on the specific service execution context. Organizations must prioritize applying vendor-supplied security updates and hardening local access controls to mitigate unauthorized privilege escalation attempts targeting installation subsystems.",
  "technicalDetails": "The vulnerability is fundamentally a stack-based buffer overflow occurring within the Windows Installer service during the processing of installation packages, transform files, or internal database queries. The root cause stems from insufficient bounds checking when the vulnerable component copies user-supplied input or installer property data into fixed-size stack buffers allocated during runtime execution. When an authorized local user initiates or interacts with a crafted installation sequence containing excessively large input payloads, the target function fails to properly validate the length of the incoming data against the destination buffer capacity. This architectural oversight permits contiguous memory overwrite conditions, corrupting adjacent stack frames, including saved frame pointers and return addresses.\nThe attack flow begins with the local attacker authenticating to the target Windows environment with standard user privileges. The adversary then crafts a malicious installation package or invokes the Windows Installer API directly with malformed parameters designed to exceed the internal buffer length. Upon execution, the vulnerable function within the Windows Installer service parses the input data, triggering the stack-based buffer overflow condition. By carefully engineering the input payload, the attacker can overwrite the return address on the call stack to point to executable shellcode or leverage Return-Oriented Programming (ROP) chains to bypass modern exploit mitigations such as Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR).\nBecause Windows Installer frequently executes with elevated system privileges to perform administrative software deployments, achieving code execution within this context allows the attacker to inherit those elevated permissions. Post-exploitation impact includes the creation of privileged local accounts, modification of critical system binaries, disabling of security controls, and total administrative dominance over the host system. The vector is strictly local, requiring the attacker to possess local interactive or programmatic access to the host, bypassing network-based perimeter defenses while heavily exploiting local trust relationships."
}