Description

Out-of-bounds read in Microsoft Office allows an unauthorized attacker to disclose information locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.5",
  "pubDate": "2026-08-11T17:18:49.787Z",
  "pubdate": "2026-08-11T17:18:49.787Z",
  "executiveSummary": "An out-of-bounds read vulnerability exists in Microsoft Office, which can be exploited by an unauthorized local attacker to achieve information disclosure. The flaw stems from improper handling of memory boundaries within the application while processing specific file structures. Successful exploitation allows an adversary to read sensitive memory contents, potentially exposing confidential data or leaking memory addresses that could facilitate further exploitation chains. The affected systems are Microsoft Office installations capable of parsing the vulnerable file formats. The attacker requires local access to the target system and must trick a user into opening a specially crafted file or leverage local execution capabilities. No authentication is inherently required beyond the ability to execute code or deliver a malicious file locally. Risk implications include the potential exposure of sensitive system memory or user data, undermining confidentiality guarantees on the host system. Mitigation relies on applying official security updates provided by the vendor and adhering to standard file-handling security practices.",
  "technicalDetails": "The vulnerability is classified as an out-of-bounds read, occurring due to inadequate bounds checking within the memory management routines of Microsoft Office components. Specifically, when the application parses malformed or specially crafted documents, it fails to properly validate the size and boundaries of input data against allocated buffer dimensions. This root cause allows read operations to access memory addresses outside the intended buffer boundaries.\nThe vulnerable component resides within the file parsing and rendering engine of Microsoft Office. The attack flow begins when an unauthorized local attacker crafts a malicious file containing manipulated structural metadata designed to trigger the out-of-bounds condition. Upon opening the file locally, the parsing engine reads the malicious size or offset parameters without validating them against the actual heap or stack buffer allocation. As a result, the application attempts to read memory beyond the legitimate limits of the buffer.\nThe payload behavior involves capturing adjacent memory contents, which may include sensitive data structures, plaintext credentials, or internal application state information. Depending on how the application handles the returned out-of-bounds data, this information may be leaked back to the user interface, written to debug logs, or exposed to the execution context controlled by the attacker. Privilege and authentication requirements are minimal; the attacker must have local access to execute the application or induce a local user to open the crafted file. Network exposure is not strictly required since the vulnerability manifests locally during file processing. The post-exploitation impact is primarily centered on information disclosure, enabling the adversary to gather intelligence or bypass localized memory randomization protections by leveraging leaked pointers."
}