CVE-2026-97772 in Excel
Summary
by MITRE • 10/15/2026
Double free in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability described involves a critical memory management error within the Microsoft Office Excel application, specifically categorized as a double free condition. This type of flaw occurs when a program attempts to deallocate or release a block of memory that has already been freed by a previous operation. In the context of complex software like Microsoft Office, which handles intricate data structures for spreadsheets and formulas, such errors can arise during the parsing or rendering of maliciously crafted files. When an attacker provides a specially constructed Excel file containing malformed objects or corrupted metadata, the application may process these inputs in a way that triggers multiple deallocation calls on the same memory address. This violates fundamental principles of safe memory management and leads to undefined behavior within the application's runtime environment.
From a technical perspective, double free vulnerabilities are particularly dangerous because they can corrupt heap data structures used by the operating system for managing dynamic memory allocation. By carefully controlling the contents of the freed memory blocks before triggering the second free operation, an attacker can manipulate these internal structures. This manipulation often allows for arbitrary code execution with the privileges of the user running the application. The vulnerability is classified under CWE-415, which defines double free as a specific instance where freeing a pointer twice leads to heap corruption and potential exploitation. Such flaws are frequently associated with CWE-787, out-of-bounds write vulnerabilities, as the corrupted memory state can lead to writes in unintended memory locations, further facilitating control flow hijacking techniques like return-oriented programming or direct shellcode injection.
The operational impact of this vulnerability is severe due to its potential for remote code execution over a network. If an attacker can trick a user into opening a malicious Excel file hosted on a web server or received via email, the exploit chain can be triggered automatically upon rendering certain elements within the document. This capability allows unauthorized attackers to gain full control over the affected system, potentially leading to data theft, installation of malware, pivoting to other systems on the network, and complete compromise of organizational security posture. The ability to execute code remotely makes this a high-severity issue that requires immediate attention from security operations teams. It aligns with MITRE ATT&CK techniques related to initial access through spearphishing attachment (T1566) and execution via user interaction (T1204), highlighting the need for robust input validation and sandboxing strategies in office productivity suites.
Mitigation strategies should focus on both immediate remediation and long-term architectural improvements. Organizations must ensure that Microsoft Office applications are updated to the latest versions containing patches specifically addressing this double free flaw, as vendors typically release security updates to fix such memory corruption issues promptly. Administrators should also implement application whitelisting policies to restrict the execution of untrusted scripts or macros within Excel files unless explicitly approved by users. Additionally, deploying advanced endpoint detection and response solutions can help identify anomalous behavior associated with exploit attempts, such as unusual process creation patterns following file opening events. Users must be educated on recognizing suspicious attachments and avoiding interaction with documents from unknown sources to reduce the attack surface effectively.