CVE-2025-49687: Critical Privilege Escalation Vulnerability in Microsoft Input Method Editor (IME)

Overview

The vulnerability under discussion, CVE-2025-49687, is a serious security flaw found in Microsoft Input Method Editor (IME), which, if successfully exploited, allows an authenticated attacker to elevate their privileges locally. It is an out-of-bounds read vulnerability, a type of flaw that enables an attacker to read data they shouldn’t have access to. This vulnerability is especially significant because it affects a wide range of users, given the widespread use of Microsoft’s software. The potential for system compromise and data leakage makes this vulnerability a critical cybersecurity risk that needs immediate attention.

Vulnerability Summary

CVE ID: CVE-2025-49687
Severity: Critical (8.8 CVSS score)
Attack Vector: Local
Privileges Required: Low
User Interaction: Required
Impact: Potential system compromise and data leakage

Affected Products

Product | Affected Versions

Microsoft Input Method Editor | All previous versions up to the latest update

How the Exploit Works

The exploit takes advantage of an out-of-bounds read vulnerability within the Microsoft Input Method Editor. An attacker, who already has low-level access to the system, can manipulate the IME to read data beyond its boundary. This data may contain sensitive information, including privileged system data. Using this information, the attacker can further exploit the system, potentially leading to a full system compromise or data leakage.

Conceptual Example Code

In the context of this vulnerability, the exploit might look conceptually like the following pseudocode:

def exploit():
initialize_IME()
create_buffer_overflow()
read_out_of_bounds_data()
use_data_to_elevate_privileges()

In this pseudocode, the attacker initializes the IME, creates a condition that leads to a buffer overflow, reads data that should be out of bounds, and then uses that data to elevate their privileges on the system.
It is important to note that this is a conceptual example, and the actual exploit would require a more sophisticated understanding of the system internals and the IME.

Mitigation and Prevention

The primary mitigation for this vulnerability is to apply the vendor-supplied patch. Microsoft has released a patch that addresses this specific vulnerability in the Input Method Editor. If the patch cannot be applied immediately, using a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can serve as temporary mitigation. These tools can detect and block attempts to exploit known vulnerabilities. However, they should not be considered a long-term solution, as they may not be able to fully prevent a dedicated and skilled attacker from exploiting this vulnerability. The most secure resolution is to apply the provided patch as soon as possible.