Introduction
Microsoft Excel, a cornerstone of productivity software, faces a critical security challenge with CVE-2025-30381, an out-of-bounds read vulnerability. This flaw, rated at a CVSS score of 7.8, allows attackers to execute arbitrary code locally, posing significant risks to data confidentiality, integrity, and system availability.
Affected Systems and Versions
The vulnerability specifically impacts the following Microsoft Excel versions:
- Microsoft Excel 2016
- Microsoft Excel 2019
- Microsoft Excel 2021
- Microsoft Excel 2024
- Microsoft 365 Apps
Systems running these Excel versions without the May 2025 security updates are vulnerable.
Technical Information
CVE-2025-30381 is rooted in Excel's improper handling of memory boundaries during file parsing. Attackers exploit this by crafting Excel files with manipulated cell data offsets. When Excel processes these files, it inadvertently reads memory beyond the allocated buffer, leading to potential memory corruption and arbitrary code execution.
The attack vector is local, requiring user interaction—specifically, opening a maliciously crafted Excel file. Upon successful exploitation, attackers can execute code with the privileges of the affected user, potentially leading to further system compromise.
Patch Information
Microsoft has addressed this vulnerability in their May 2025 Patch Tuesday updates. Users should immediately apply the KB5002695 update for affected Excel versions. The patch can be obtained directly from Microsoft's official update channels:
Organizations unable to immediately patch should implement alternative mitigations, such as restricting user privileges, employing application allow-listing, and educating users on the dangers of opening files from unknown sources.
Detection Methods
Currently, specific detection methods or indicators of compromise for CVE-2025-30381 have not been publicly detailed. Organizations should monitor for unusual Excel crashes or unexpected behavior when opening files, as these may indicate attempted exploitation.
Vendor Security History
Microsoft has previously faced similar vulnerabilities in Excel, such as CVE-2016-0122, which was actively exploited shortly after disclosure. Microsoft's regular Patch Tuesday updates demonstrate a proactive approach to addressing vulnerabilities, though the recurrence of memory-handling issues highlights ongoing security challenges.
References
Organizations are urged to prioritize patching and remain vigilant against potential exploitation attempts, given Excel's widespread use and historical attractiveness as a target for threat actors.
