CVE-2026-80078 in 365 Apps for Enterprise
Summary
by MITRE • 09/09/2026
Out-of-bounds read in Microsoft Office allows an unauthorized attacker to disclose information over a network.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability described constitutes a critical security flaw within the Microsoft Office suite, specifically categorized as an out-of-bounds read error. This type of memory corruption issue arises when software attempts to access data at a memory location that lies outside the boundaries of the intended buffer or array structure. In the context of document processing applications like Word, Excel, or PowerPoint, such errors often occur during the parsing and rendering of complex file formats. When an attacker crafts a maliciously constructed Office document containing specially designed elements, they can trigger this out-of-bounds read condition within the application's memory space. The primary consequence of this flaw is the unauthorized disclosure of sensitive information over a network or local system context. By exploiting this vulnerability, an adversary can potentially leak contents from adjacent memory regions that were not intended to be accessed by the user or the application logic. This could include credentials, encryption keys, session tokens, or other proprietary data residing in the process memory at the time of exploitation.
From a technical perspective, out-of-bounds reads are frequently associated with CWE-125, which defines an out-of-bounds read as accessing memory beyond the end of a buffer without executing arbitrary code. Unlike more severe vulnerabilities such as heap overflows that allow for remote code execution, this specific flaw primarily facilitates information disclosure rather than direct system compromise. However, in modern security architectures where data is often shared across processes or cached in memory, even an information leak can serve as a critical stepping stone for further attacks. For instance, leaked cryptographic material could be used to decrypt intercepted communications, while exposed session identifiers might allow for account takeover via session hijacking techniques. The vulnerability highlights the complexity of managing memory safety in legacy codebases that have evolved over decades without complete refactoring into safer abstractions.
The operational impact of this vulnerability is significant because it affects a ubiquitous productivity tool widely used across enterprise environments. Users who open maliciously crafted documents, whether through email attachments, shared network drives, or web downloads, are at risk of having their system's memory contents partially exposed to the attacker. This exposure does not necessarily result in immediate data loss but creates a persistent security gap that can be leveraged for reconnaissance and lateral movement within an organization. The ability to read arbitrary memory locations undermines the confidentiality guarantees provided by operating systems and application sandboxing mechanisms, as it bypasses standard access controls through logical errors rather than privilege escalation techniques.
To mitigate this risk, organizations must prioritize immediate patching of all Microsoft Office installations with the latest security updates released by Microsoft. These patches typically include bounds checking improvements and input validation enhancements that prevent the application from accessing invalid memory addresses during document parsing. Administrators should also enforce strict email filtering policies to block attachments containing suspicious macros or embedded objects that might trigger such vulnerabilities. Additionally, implementing application whitelisting can restrict the execution of untrusted Office components, thereby reducing the attack surface available to potential exploiters. Regular security awareness training for end-users is equally critical, as social engineering remains a primary vector for delivering malicious documents that leverage this and similar memory corruption flaws. Monitoring network traffic for anomalous data exfiltration patterns related to office application processes can also aid in early detection of exploitation attempts before significant damage occurs.