Description

Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to disclose information locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.5",
  "pubDate": "2026-08-11T17:19:02.493Z",
  "pubdate": "2026-08-11T17:19:02.493Z",
  "executiveSummary": "A heap-based buffer overflow vulnerability exists within Microsoft Office Word, specifically affecting the processing of specially crafted document files. This memory corruption flaw allows an unauthorized, local attacker to facilitate unauthorized information disclosure on vulnerable systems. The primary risk implication centers on the potential leakage of sensitive memory contents, which could expose critical system data, user credentials, or application internals to malicious actors. Successful exploitation requires an attacker to convince a user to open a maliciously formatted document file utilizing the vulnerable software. The attack surface is localized, necessitating local access or a mechanism to deliver the payload to the victim machine, such as via email or local network shares. Because the vulnerability involves out-of-bounds read or memory exposure resulting from a heap overflow condition, it undermines the confidentiality guarantees of the affected host environment. Remediation typically involves applying official vendor patches or updates addressing memory management within the parsing engine of Microsoft Office Word.",
  "technicalDetails": "The vulnerability is classified as a heap-based buffer overflow stemming from improper bounds checking during the parsing of specific data structures within Microsoft Office Word files. The vulnerable component resides in the document parsing and memory allocation routines responsible for handling complex file formats or embedded objects. When Microsoft Office Word processes a malformed document containing malicious payloads designed to manipulate heap allocations, the application fails to accurately calculate the required buffer size before writing data to dynamically allocated heap memory. This results in data being written beyond the boundaries of the allocated heap chunk, corrupting adjacent heap metadata or adjacent memory structures. In the context of this vulnerability, the exploitation mechanism leverages this out-of-bounds condition to read sensitive memory contents residing on the heap rather than achieving arbitrary code execution. The attack flow begins when a user opens the untrusted document using a vulnerable version of Microsoft Office Word. Upon opening, the parsing engine attempts to decode the structural elements of the file, triggering the flawed memory allocation routine. As the application processes the malformed input, adjacent heap memory areas are inadvertently exposed or read due to the over-read condition. The attacker can then potentially retrieve this sensitive information, leading to local information disclosure. The vulnerability requires no authentication or specialized privileges to exploit locally, other than the ability to deliver and execute the malicious file within the context of the local user. Network exposure is indirect, as exploitation relies on local file processing, though the file itself may be delivered across a network. Post-exploitation impact is strictly confined to the leakage of information residing in the heap memory space of the affected process, which may facilitate subsequent multi-stage attacks if valuable data is harvested."
}