CVE-2025-59295: 
vulnerability analysis and mitigation

A high-severity Remote Code Execution (RCE) vulnerability, identified as CVE-2025-59295, was discovered in the Windows URL Parsing functionality. The vulnerability is tied to the legacy MSHTML platform (Internet Explorer's Trident engine) and has been assigned a CVSS 3.1 base score of 8.8 HIGH. The vulnerability affects all supported versions of Windows and was disclosed on October 14, 2025 (NVD, Lansweeper).

The vulnerability is classified as CWE-122: Heap-based Buffer Overflow, which occurs when the application processes a specially crafted URL and writes more data to a memory buffer on the heap than has been allocated. While Internet Explorer 11 desktop application is retired on most Windows versions, its core rendering engine (MSHTML.dll) remains an integrated and supported component of the operating system, used in Internet Explorer Mode in Microsoft Edge, Microsoft Office, and Third-Party Applications. The vulnerability has a CVSS vector string of CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H (NVD, Immersive Labs).

When exploited, the vulnerability allows an unauthorized attacker to execute code over a network. The overflowed data can be designed to overwrite critical program data, such as a function pointer or an object's virtual function table (vtable) pointer. When the application later attempts to use this corrupted pointer, it redirects the program's execution flow to a memory address controlled by the attacker, enabling arbitrary code execution on the target system (Immersive Labs).

The vulnerability is addressed through the Internet Explorer Cumulative Update, which is essential for all systems, including servers and those that only install Security Only updates, to ensure the underlying MSHTML component is secured. Microsoft recommends applying the IE cumulative update on all Windows machines, from servers to client installs (Immersive Labs).