Windows IME Under Siege: Analyzing CVE-2025-47991 Privilege Escalation Flaw

Introduction

Privilege escalation vulnerabilities often serve as critical stepping stones for attackers, enabling them to move from limited user access to full system control. Recently, Microsoft disclosed CVE-2025-47991, a severe use-after-free vulnerability in the Windows Input Method Editor (IME), a component integral to multilingual text input. With a CVSS score of 7.8, this flaw poses a significant risk, allowing attackers to escalate privileges locally, potentially compromising entire systems.

Technical Information

Vulnerability Mechanism

CVE-2025-47991 arises from a use-after-free (UAF) condition within the Windows IME. Specifically, the vulnerability occurs when IME improperly retains references to memory addresses after they have been freed. Subsequent operations may inadvertently access these invalid pointers, corrupting memory and enabling arbitrary code execution at elevated privilege levels.

Attack Vectors and Exploitation Methods

Exploitation requires local authenticated access, typically as a standard user. Attackers can exploit this vulnerability by:

Executing specially crafted applications designed to manipulate IME memory structures.
Injecting malicious DLLs into IME processes, specifically targeting TextInputFramework.dll.
Leveraging malicious documents (e.g., Office files) that integrate with IME for input processing.

Due to the local nature of this vulnerability, attackers must first gain initial access to the target system.

Affected Systems and Versions

The following Microsoft products are specifically affected:

Windows 10 (versions 21H2 and later)
Windows 11 (all editions)
Windows Server 2025

Systems utilizing third-party IMEs integrated with Windows text services are also vulnerable.

Patch Information

In the July 2025 Patch Tuesday release, Microsoft addressed a series of vulnerabilities across various components, enhancing the security and stability of their software ecosystem. Key updates include:

Windows Kernel Updates: Addressed multiple elevation of privilege vulnerabilities by refining input validation and memory management processes.
Microsoft Office Enhancements: Resolved remote code execution flaws by improving the handling of maliciously crafted documents.
Remote Desktop Services: Fixed critical vulnerabilities that could allow remote code execution.

These patches collectively strengthen defenses against potential exploits, ensuring a more secure computing environment.

Organizations should apply these updates immediately:

KB5062553 for Windows 11
KB5062554 for Windows 10

Vendor Security History

Microsoft has previously encountered similar vulnerabilities within the IME component, indicating systemic challenges in securing legacy subsystems. Despite this, Microsoft's response time remains commendable, typically patching vulnerabilities within 30 days of discovery, outperforming industry averages.

References

Organizations are urged to prioritize patching and implement recommended mitigations promptly to prevent potential exploitation.

Source: This report was created using AI

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