CVE-2025-47991: Critical Privilege Escalation Vulnerability in Microsoft IME

Overview

CVE-2025-47991 is a significant cybersecurity vulnerability related to the use-after-free issue in Microsoft’s Input Method Editor (IME). This flaw allows an authorized attacker to escalate privileges locally, which could potentially compromise the system or result in data leakage. Given the broad usage of Microsoft’s software in businesses and personal computing worldwide, this vulnerability poses a significant risk to a vast number of users. It is crucial for users and administrators to understand this vulnerability and take necessary steps to mitigate the risk.

Vulnerability Summary

CVE ID: CVE-2025-47991
Severity: High (7.8 CVSS Score)
Attack Vector: Local
Privileges Required: Low
User Interaction: Required
Impact: System compromise or data leakage

Affected Products

Product | Affected Versions

Microsoft IME | All versions prior to the latest patch

How the Exploit Works

The vulnerability stems from a use-after-free condition within the Microsoft IME. In simple terms, the software incorrectly manages memory allocations, resulting in the possibility that an attacker could reference memory after it has been freed. This can lead to unexpected behaviors such as the system crashing or, in certain circumstances, the execution of unauthorized code. An attacker who successfully exploits this vulnerability can run arbitrary code in the context of the current user. If the current user is logged on with administrative user rights, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

Conceptual Example Code

While the exact exploit code is not provided due to ethical concerns, the exploitation process would conceptually involve the misuse of the memory allocation and deallocation within the application, similar to the following pseudocode:

allocate_memory(object)
use_object(object)
free_memory(object)
use_object(object) // Use after free vulnerability

In the above pseudocode, the object is used even after its associated memory has been freed, resulting in undefined behavior, which could be manipulated by an attacker to execute malicious code.

Mitigation Guidance

The most effective way to mitigate this vulnerability is to apply the patches provided by Microsoft. If a patch cannot be applied immediately, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) could serve as a temporary mitigation. However, these measures may not fully prevent an exploit and are not a substitute for patching the system. Regular patch management, combined with robust cybersecurity practices, are crucial to maintaining a secure IT environment.