Description

Heap-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": "2026-08-11T17:18:50.310Z",
  "pubdate": "2026-08-11T17:18:50.310Z",
  "executiveSummary": "This vulnerability is classified as a heap-based buffer overflow affecting Microsoft Office. The security flaw allows an unauthorized attacker to achieve local code execution on target systems.\nThe primary risk implication is complete system compromise within the security context of the locally logged-in user. If successfully exploited, the vulnerability grants the adversary the ability to execute arbitrary native instructions, potentially leading to unauthorized data access, persistence installation, and lateral movement.\nThe affected product is Microsoft Office. Exploitation requires local access or user interaction to process a maliciously crafted document or file format handled by the vulnerable application components.\nAttackers do not require prior authentication to trigger the flaw, provided they can deliver the malicious payload to the local system and induce the victim to open it. The vulnerability underscores the risks associated with parsing complex file formats within memory-unsafe routines inside office productivity suites.",
  "technicalDetails": "The vulnerability resides in a memory management routine within Microsoft Office responsible for processing specific structured data fields or file formats. The root cause is a heap-based buffer overflow, stemming from inadequate bounds checking when allocating and writing data to dynamic memory buffers on the heap.\nWhen the vulnerable application parses a maliciously crafted file, it miscalculates the required buffer size for incoming data structures. Consequently, the application writes more data into the heap-allocated buffer than it can hold, resulting in a heap overflow condition.\nThis overflow corrupts adjacent heap metadata, control structures, or critical application data residing in contiguous memory chunks. An attacker can carefully craft the input payload to manipulate heap layout, overwrite function pointers, or corrupt virtual method tables (vptrs).\nThe attack flow proceeds as follows: First, the unauthorized local attacker delivers the weaponized file to the target system via removable media, local network shares, or social engineering vectors. Second, the user opens the file using the vulnerable Microsoft Office application. Third, the application initiates parsing of the malformed data structures.\nFourth, during parsing, the insufficient boundary validation triggers the heap-based buffer overflow. Fifth, the overwritten memory structures hijack control flow when the application attempts to execute a corrupted function pointer or dereference a manipulated object reference.\nFinally, execution is redirected to attacker-supplied shellcode or Return-Oriented Programming (ROP) chains residing in memory. The payload executes with the privileges of the current user session, enabling local code execution and subsequent post-exploitation activities without requiring elevated administrative privileges or network exposure."
}