CVE-2026-65657 in Office 365 Apps for Enterprise
Summary
by MITRE • 08/11/2026
Use after free in Microsoft Office allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 08/12/2026
This vulnerability represents a critical use-after-free condition in Microsoft Office applications that enables remote code execution through local privilege escalation. The flaw occurs when the application fails to properly validate memory references after objects have been freed, creating opportunities for attackers to manipulate memory contents and execute arbitrary code with elevated privileges. Such vulnerabilities typically arise from insufficient null pointer checks or improper object lifecycle management within the application's memory handling mechanisms.
The technical exploitation of this use-after-free vulnerability follows established patterns documented in CWE-416, which specifically addresses use-after-free conditions in software systems. Attackers can craft malicious Office documents that trigger the vulnerable code path when opened, causing the application to free memory associated with certain objects while still maintaining references to them. This creates a scenario where subsequent operations can overwrite freed memory regions with attacker-controlled data, ultimately leading to code execution.
From an operational perspective, this vulnerability presents significant risk as it requires minimal user interaction for exploitation. Once a malicious document is opened, the attacker gains local code execution capabilities that may escalate privileges to system level access depending on the target environment. The attack vector aligns with ATT&CK technique T1059 for command and scripting interpreter usage, as successful exploitation could enable attackers to execute commands through compromised Office processes.
The impact extends beyond immediate code execution to include potential persistence mechanisms and lateral movement capabilities within compromised environments. Organizations running affected Microsoft Office versions face elevated risk of data breaches and system compromise, particularly in environments where users have administrative privileges or where Office applications are frequently used with potentially untrusted content. The vulnerability's exploitation often bypasses standard security controls due to the legitimate nature of Office application processes.
Effective mitigation strategies include immediate deployment of Microsoft security updates that address the specific memory handling flaws, implementation of application control policies limiting Office application functionality, and regular security awareness training to reduce successful social engineering attacks. Organizations should also consider deploying exploit prevention technologies such as address space layout randomization and data execution prevention mechanisms. Additionally, network segmentation and privilege minimization practices help reduce the potential impact of successful exploitation by limiting what an attacker can access even after gaining code execution privileges within a compromised Office application.