CVE-2026-97745 in Office
Summary
by MITRE • 10/15/2026
Use after 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 constitutes a critical security flaw within the Microsoft Office Excel application, specifically involving a use-after-free condition that can be exploited remotely by an unauthenticated attacker. This type of defect arises when software continues to reference memory after it has been freed or deallocated, leading to undefined behavior that attackers can manipulate for malicious purposes. In the context of network-based attacks, this vulnerability typically manifests through specially crafted files or data streams processed by Excel during normal operation, such as opening a document containing complex formulas, embedded objects, or malformed metadata. The exploitation chain often involves tricking a user into interacting with a malicious file, which triggers the memory corruption sequence when Excel attempts to access the previously freed memory region.
From a technical perspective, use-after-free vulnerabilities are particularly dangerous because they allow an attacker to control how the application interprets data in memory after it has been released back to the system allocator. By carefully crafting the payload, an attacker can overwrite adjacent heap structures or inject shellcode into the reclaimed memory space. When Excel subsequently accesses this corrupted pointer, it may execute arbitrary code with the privileges of the current user process. This mechanism bypasses many standard security controls because the execution occurs within a trusted application context, effectively granting the attacker full control over the compromised system without requiring elevated permissions initially.
The operational impact of this vulnerability is severe, as it enables remote code execution (RCE) across network boundaries. An adversary could exploit this flaw to install malware, steal sensitive data, create new user accounts with administrative privileges, or use the infected machine as a pivot point for further lateral movement within an organization's internal network. Given that Excel is widely used in enterprise environments and frequently handles documents received via email or shared drives, the attack surface is extensive. The ability to execute code over the network means that physical access to the target system is not required, significantly increasing the risk of widespread compromise if patching procedures are delayed or misconfigured.
To mitigate this risk, organizations must prioritize the immediate deployment of security updates provided by Microsoft for all affected versions of Office Excel. Administrators should ensure that automatic update mechanisms are enabled and functioning correctly across all endpoints to minimize the window of exposure. Additionally, implementing application control policies can restrict the execution of untrusted scripts or macros, reducing the likelihood of successful exploitation even if a vulnerable version is present. Users should be educated on social engineering tactics and advised not to open documents from unknown sources. Network segmentation and intrusion detection systems monitoring for anomalous Excel behavior can also provide an additional layer of defense against active exploits targeting this vulnerability.
This flaw aligns with Common Weakness Enumeration (CWE) identifier CWE-416, which defines use-after-free errors as a category of memory corruption vulnerabilities where pointers are used after they have been freed. In terms of the MITRE ATT&CK framework, exploitation techniques associated with such flaws often fall under Tactic 12: Impact or Tactic 7: Command and Control, specifically involving remote code execution via software exploits like CVE-identified defects in productivity suites. Understanding these classifications helps security teams map defenses to specific threat behaviors and prioritize remediation efforts based on the potential for lateral movement and persistent access establishment by adversaries leveraging this memory corruption flaw.