CVE-2025-54899: 
vulnerability analysis and mitigation

CVE-2025-54899 is a Remote Code Execution (RCE) vulnerability in Microsoft Excel that was disclosed in September 2025. The vulnerability is caused by freeing memory not on the heap in Microsoft Excel, which can lead to local code execution. This vulnerability is classified as Important severity and affects Microsoft Excel installations (Cybersecurity News, GBHackers).

The vulnerability is related to memory management issues in Microsoft Excel, specifically involving freeing memory not on the heap. This improper memory handling can be exploited to achieve local code execution on affected systems. The vulnerability has been assigned an Important severity rating, indicating a significant but not critical level of risk. It is one of seven RCE vulnerabilities (CVE-2025-54896, CVE-2025-54898, CVE-2025-54899, CVE-2025-54900, CVE-2025-54902, CVE-2025-54903, CVE-2025-54904) patched in Microsoft Excel during the September 2025 Patch Tuesday updates (Cybersecurity News, Bleeping Computer).

If successfully exploited, this vulnerability allows an attacker to execute arbitrary code in the local context. The attack requires user interaction, as it can be triggered when a user opens a specially crafted Excel file (Cybersecurity News).

Microsoft has released a patch for this vulnerability as part of the September 2025 Patch Tuesday security updates. System administrators are strongly urged to apply these security updates promptly to mitigate the risk (GBHackers).