CVE-2025-53739 in Excel
Summary
by MITRE • 08/12/2025
Access of resource using incompatible type ('type confusion') in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 08/16/2025
The vulnerability identified as CVE-2025-53739 represents a critical type confusion flaw within Microsoft Office Excel that enables remote code execution through maliciously crafted spreadsheet files. This issue stems from improper handling of data types during memory operations, creating a condition where the application attempts to access resources using incompatible data type specifications. The flaw exists in Excel's parsing mechanisms for various file formats including xls, xlsx, and xlsm, making it particularly dangerous as attackers can exploit this through multiple attack vectors.
Type confusion vulnerabilities fall under the CWE-415 category, specifically CWE-415: Double Free, though in this case the underlying mechanism involves improper type handling rather than direct memory management errors. The vulnerability manifests when Excel encounters malformed data structures within spreadsheet files where the application's internal type checking fails to properly validate data types before processing operations. This misalignment allows attackers to manipulate memory layout and execute arbitrary code with the privileges of the victim user. The ATT&CK framework categorizes this under T1059.001 for command and scripting interpreter and T1203 for Exploitation for Client Execution, as it enables attackers to execute malicious payloads through legitimate Office applications.
The operational impact of CVE-2025-53739 is severe as it allows for local privilege escalation and persistent code execution within the victim's environment. Attackers can craft malicious Excel files that, when opened by an unsuspecting user, trigger the type confusion vulnerability and execute malicious payloads directly on the target system. The exploitation requires minimal user interaction beyond opening the infected file, making it particularly effective for social engineering campaigns. Once executed, the malicious code can establish persistence mechanisms, exfiltrate sensitive data, or pivot to other systems within the network. The vulnerability affects all supported versions of Microsoft Office, including Excel 2016, 2019, 2021, and Microsoft 365, with the potential for widespread impact across enterprise environments.
Mitigation strategies for CVE-2025-53739 should include immediate deployment of Microsoft's security patches and updates, as well as implementing administrative controls to restrict Excel file execution. Organizations should deploy application whitelisting solutions to prevent execution of untrusted Office documents and configure Office applications to disable macro execution by default. Network-based protections such as email filtering and web proxy configurations should be enhanced to block suspicious Office file attachments. Security teams should also implement monitoring for unusual Excel process behavior and file access patterns. The recommended approach combines multiple defensive layers including endpoint protection, network security controls, and user education to minimize the risk of exploitation. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar type confusion vulnerabilities in other Microsoft Office applications.