Description

Stack-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.8",
  "pubDate": "2026-08-11T17:19:02.107Z",
  "pubdate": "2026-08-11T17:19:02.107Z",
  "executiveSummary": "This security assessment analyzes a stack-based buffer overflow vulnerability residing within Microsoft Office. The flaw allows an unauthorized, locally authenticated threat actor to achieve arbitrary code execution on target systems.\nThe vulnerability stems from improper bounds checking during the parsing of malicious input within the affected software component. If successfully exploited, an adversary can execute arbitrary machine code in the context of the currently logged-in user, potentially leading to complete system compromise, privilege escalation, or data exfiltration.\nExploitation requires local access to the target machine and typically involves tricking a user into opening a specially crafted file using a vulnerable version of Microsoft Office. The risk implications are severe due to the potential for local code execution and subsequent system manipulation.\nDefense strategies must focus on applying official vendor patches, enforcing strict application integrity controls, and monitoring for anomalous process execution behaviors associated with the Office suite.",
  "technicalDetails": "The vulnerability is classified as a stack-based buffer overflow, occurring when a vulnerable function within Microsoft Office copies input data into a fixed-length memory buffer on the stack without adequately validating the input size.\nThe root cause is the absence of rigorous bounds checking before memory write operations, allowing input streams to exceed allocated buffer boundaries and overwrite adjacent stack memory, including saved frame pointers and return addresses.\nThe vulnerable component is a specific internal module responsible for processing structured file formats or data structures within Microsoft Office. Exploitation occurs step-by-step as follows: first, an attacker delivers a maliciously crafted file to the target system via local storage or removable media. Second, the user opens the file using a vulnerable installation of Microsoft Office. Third, the application parses the malformed structure, triggering the vulnerable function. Fourth, the oversized input overflows the stack buffer, corrupting critical control data structures.\nBy carefully crafting the payload, the attacker can overwrite the return instruction pointer with the address of malicious shellcode or execute a return-oriented programming (ROP) chain. Upon function return, execution flow is redirected to the attacker's payload.\nAuthentication requirements are minimal, as the attack vector relies on local code execution or user interaction via file opening rather than network authentication. Privilege requirements are limited to standard user rights, meaning the payload executes with the privileges of the affected user process. Network exposure is non-existent by default since the vulnerability is locally exploitable.\nPost-exploitation impact includes localized arbitrary code execution, installation of persistent malware, unauthorized access to sensitive user data, and potential lateral movement if the compromised user holds elevated domain privileges."
}