CVE-2026-68799 in 365 Apps for Enterprise
Summary
by MITRE • 08/12/2026
Use of uninitialized resource in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.
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Analysis
by VulDB Data Team • 08/12/2026
This vulnerability represents a critical security flaw in Microsoft Office Excel that arises from the improper handling of uninitialized resources during spreadsheet processing operations. The issue occurs when Excel attempts to access memory locations or data structures that have not been properly initialized before use, creating potential pathways for information disclosure attacks. Such vulnerabilities typically stem from inadequate input validation and memory management practices within the application's codebase, particularly in components responsible for parsing spreadsheet files and rendering graphical elements.
The technical implementation of this vulnerability involves scenarios where Excel processes malformed or specially crafted spreadsheet files containing maliciously constructed data structures. When the application encounters uninitialized variables or memory segments during file parsing operations, it may inadvertently expose sensitive information from adjacent memory locations to attackers. This occurs because the program fails to properly initialize memory before reading from or writing to these locations, potentially leaking system information, cryptographic keys, or other confidential data that resides in nearby memory regions.
From an operational perspective, this vulnerability poses significant risks to enterprise environments where Microsoft Office applications are widely deployed. Attackers can leverage this flaw by crafting malicious excel files designed to trigger the uninitialized resource access during normal document processing operations. The local information disclosure aspect means that successful exploitation requires minimal network exposure since the attack vector operates within the confines of a user's local system. This makes it particularly dangerous in environments where users frequently open spreadsheets from untrusted sources, as the vulnerability can be triggered simply by opening a malicious file.
The impact of such vulnerabilities aligns with CWE-457, which specifically addresses the use of uninitialized variables in software applications, and can be mapped to ATT&CK technique T1059.005 for execution through office applications. Organizations face potential data breaches where sensitive corporate information, user credentials, or system configurations could be exposed through this vector. The vulnerability's classification as a local information disclosure means that attackers typically need physical access or the ability to execute malicious code on a target system, though social engineering campaigns can facilitate initial compromise through phishing attacks targeting office application usage patterns.
Mitigation strategies should include immediate deployment of Microsoft security patches and updates to address the specific uninitialized resource handling issues. Organizations should implement strict file validation policies, disable automatic execution of macros in office applications, and establish comprehensive monitoring for suspicious file access patterns. Additional protective measures involve regular security training for employees to recognize potentially malicious spreadsheet files and maintaining up-to-date endpoint protection solutions that can detect anomalous behavior associated with exploitation attempts. Network segmentation and principle of least privilege access controls further reduce the potential impact should an attacker successfully exploit this vulnerability, while regular security assessments help identify additional exposure points in office application configurations.