CVE-2026-97767 in Office
Summary
by MITRE • 10/15/2026
Double free in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 10/15/2026
The vulnerability described involves a double-free memory corruption flaw within the Microsoft Office Excel application, specifically affecting components responsible for parsing and rendering spreadsheet data. This type of error occurs when a program attempts to release a block of allocated memory more than once without properly resetting the pointer or checking its status between deallocations. In the context of Excel, this likely stems from complex object handling during the processing of maliciously crafted files that exploit edge cases in how internal structures are managed and destroyed. The presence of such a flaw indicates insufficient validation of state transitions within the memory management subsystems of the application, allowing an attacker to manipulate the heap layout through carefully constructed input data.
From a technical perspective, double-free vulnerabilities are particularly dangerous because they can lead to arbitrary code execution with elevated privileges depending on the context in which the vulnerable process runs. When memory is freed twice, it often results in corruption of internal metadata structures such as free lists or allocation headers. An attacker who controls this corrupted state can potentially overwrite adjacent heap chunks, leading to control flow hijacking techniques like return-oriented programming (ROP) or direct function pointer overwrites. This mechanism allows the execution of arbitrary shellcode injected via the malicious document file, effectively bypassing standard security boundaries that rely on memory safety assumptions.
The operational impact of this vulnerability is severe due to its network-based exploitability vector. Since Microsoft Office applications are frequently used to open documents received via email or downloaded from untrusted sources, an attacker can distribute a specially crafted Excel file through phishing campaigns or compromised websites. Upon opening the malicious document, the application processes the embedded data structures that trigger the double-free condition. If successful, this leads to remote code execution on the victim's machine without any further interaction required beyond opening the file. This significantly lowers the barrier for entry for attackers and increases the potential blast radius of a single compromised endpoint within an enterprise network.
This vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-415, which defines Double Free as releasing memory twice in sequence without proper reinitialization or nullification of pointers. It also maps to MITRE ATT&CK technique T1203, Exploitation for Client Execution, where attackers leverage vulnerabilities in client software to execute malicious code on target systems. The exploitation path typically involves social engineering combined with technical payload delivery, making it a critical threat vector against end-users who may not have advanced security awareness or protective controls enabled by default.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Organizations should immediately apply the latest cumulative updates provided by Microsoft to patch this specific flaw in Excel components. Administrators are advised to enable Protected View for files originating from the internet, which isolates document processing in a sandboxed environment with restricted permissions, thereby preventing exploitation even if the vulnerability is present. Additionally, implementing application whitelisting and restricting macro execution can reduce the attack surface by limiting the ability of malicious scripts embedded within documents to execute code on the host system. Regular security awareness training for employees regarding phishing tactics remains essential as technical controls alone cannot fully mitigate social engineering-driven delivery mechanisms associated with such vulnerabilities.