CVE-2025-53735 in Excel
Summary
by MITRE • 08/12/2025
Use after free 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-2025-53735 represents a critical use-after-free flaw in Microsoft Office Excel that enables remote code execution through maliciously crafted spreadsheet files. This vulnerability exists within the memory management mechanisms of Excel's parsing engine when processing specific file formats, particularly those containing malformed or specially constructed objects within workbook structures. The flaw arises from improper handling of memory allocation and deallocation processes, creating a scenario where freed memory regions can be accessed and manipulated by an attacker after they have been released from the application's memory space. Such conditions typically occur when Excel processes complex spreadsheet elements like charts, pivot tables, or embedded objects that trigger memory cleanup operations while simultaneously allowing subsequent access to the same memory locations through crafted input data.
The technical implementation of this vulnerability follows a classic use-after-free pattern where an attacker crafts an Excel file containing malicious data structures that cause Excel to allocate memory for certain objects, process them, and then free the memory. However, due to inadequate memory management controls, the application continues to reference these freed memory locations during subsequent operations, leading to potential code execution. This type of vulnerability is classified under CWE-416 as "Use After Free" and is particularly dangerous because it can be exploited through social engineering attacks where users open malicious files, making it a prime target for phishing campaigns and targeted attacks. The exploitation process typically involves precise memory layout manipulation to ensure that freed memory regions are reused in a controlled manner that allows arbitrary code execution with the privileges of the compromised user.
The operational impact of CVE-2025-53735 extends beyond simple local privilege escalation as it enables attackers to execute arbitrary code on vulnerable systems without requiring elevated privileges initially. Once exploited, the malicious code can perform various malicious activities including data exfiltration, establishing persistence mechanisms, installing additional malware, or creating backdoors for further access. The vulnerability affects multiple versions of Microsoft Office Excel across different operating systems, making it particularly attractive to threat actors seeking broad exploitation coverage. Attackers can leverage this vulnerability through various delivery methods including email attachments, malicious websites, or compromised documents shared through collaboration platforms. The attack surface is significantly expanded due to Excel's widespread use in business environments and the common practice of opening spreadsheet files from untrusted sources, creating numerous potential entry points for compromise.
Mitigation strategies for CVE-2025-53735 should prioritize immediate patch management through Microsoft's security updates, which typically address the underlying memory management issues by implementing proper memory deallocation controls and validation checks. Organizations should implement comprehensive email filtering and sandboxing solutions to prevent users from opening potentially malicious Excel files, while also maintaining strict access controls and network segmentation to limit lateral movement if exploitation occurs. Security teams should monitor for indicators of compromise including unusual network connections, file creation patterns, and process behavior that may signal exploitation attempts. Additional protective measures include disabling automatic execution of macros in Excel, implementing application control policies, and conducting regular security awareness training for users to recognize potential social engineering attempts. The vulnerability aligns with several ATT&CK techniques including initial access through malicious files, privilege escalation via code execution, and persistence mechanisms that attackers may establish once they gain a foothold in the system. Organizations should also consider implementing endpoint detection and response solutions that can identify anomalous memory access patterns and use-after-free behaviors that may indicate exploitation attempts.