Description

Use of uninitialized resource in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.5",
  "pubDate": "2026-08-11T17:19:03.527Z",
  "pubdate": "2026-08-11T17:19:03.527Z",
  "executiveSummary": "This vulnerability involves the use of an uninitialized resource within Microsoft Office Excel, a widely deployed spreadsheet processing application. The security flaw allows an unauthorized local attacker to successfully execute an information disclosure attack.\nThe primary impact of this vulnerability is the unauthorized exposure of sensitive local system or memory data, which could potentially facilitate further compromise or expose proprietary information handled within the spreadsheet environment.\nAffected systems include Microsoft Office Excel installations susceptible to uninitialized resource handling errors. The risk implications are moderate to high depending on the sensitivity of the data resident in the targeted memory spaces or accessible file paths during the execution lifecycle.\nAttacker capabilities are constrained to local access vectors, requiring the capability to execute code or manipulate specially crafted files directly on the target machine. Specific exploitation requirements involve the user or system processing a specially crafted input that triggers the improper state initialization within the application's resource management routines.",
  "technicalDetails": "The root cause of the vulnerability stems from improper initialization of memory or system resources within Microsoft Office Excel. When the application allocates resources to handle specific file structures or internal operations, certain code paths fail to assign valid initial states or values to designated memory buffers or object structures before they are read or processed.\nThe vulnerable component resides in the core resource allocation and management subsystems of Microsoft Office Excel responsible for handling document parsing and rendering states. The affected versions encompass standard builds of Microsoft Office Excel where resource initialization routines lack sufficient defensive validation checks.\nRegarding authentication and privilege requirements, the attack requires local access to the target host. The attacker needs no prior authentication to the application itself, but operating system-level execution capabilities are typically necessary to stage the exploit vector.\nThe network exposure for this specific vector is local, meaning remote exploitation over network interfaces is not inherently described by the vulnerability mechanism. However, the delivery of the malicious payload or file container could occur via remote vectors such as email attachments or shared drives, culminating in local execution.\nThe exploitation method relies on inducing the application to interact with an uninitialized resource. The step-by-step attack flow begins when an unauthorized attacker crafts a specialized input file or initiates a specific operational sequence designed to target the flawed allocation routine. Upon parsing the input, Microsoft Office Excel allocates a resource—such as a memory buffer or internal data structure—without properly clearing or initializing its contents.\nSubsequent execution logic reads from this uninitialized resource, inadvertently capturing residual data residing in memory from previous operations or adjacent memory allocations. The application then processes or reflects this residual data back through user-accessible error messages, interface elements, or saved outputs.\nThe payload behavior centers on data harvesting rather than code execution or denial of service. The post-exploitation impact is characterized by local information disclosure, wherein the attacker gains unauthorized visibility into sensitive memory contents, potentially extracting credentials, encryption keys, or internal application states."
}