CVE-2025-47971: Buffer Over-Read in Virtual Hard Disk Leading to Privilege Escalation

Overview

The vulnerability identified as CVE-2025-47971 is a crucial security flaw that primarily affects systems using Virtual Hard Disk (VHDX) technology. It allows an attacker to read more data than they should have access to, which can lead to unauthorized privilege escalation. As cyber threats are becoming more sophisticated and relentless, it is essential for network administrators, security professionals, and general users to understand the impact of such vulnerabilities. This particular vulnerability is significant because it can potentially lead to system compromise or data leakage, posing a significant risk to the confidentiality, integrity, and availability of data.

Vulnerability Summary

CVE ID: CVE-2025-47971
Severity: High (7.8 CVSS Score)
Attack Vector: Local
Privileges Required: Low
User Interaction: None
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

Windows Server | 2012, 2016, 2019
Hyper-V | All versions prior to the patch release

How the Exploit Works

This vulnerability takes advantage of a buffer over-read condition present in the handling of VHDX files. An attacker with access to the affected system can craft a specifically designed VHDX file that, when processed, forces the system to read beyond the allocated buffer. This can lead to leakage of sensitive information and, under certain conditions, can be leveraged to execute arbitrary code with elevated privileges.

Conceptual Example Code

The example below is a conceptual illustration of how a malicious VHDX file might be used to exploit the vulnerability:

# Create a malicious VHDX file
echo 'base64-encoded-payload' > malicious.vhdx
# Mount the malicious VHDX
mount -t vhdx -o loop malicious.vhdx /mnt/target
# Trigger the vulnerability
cat /mnt/target/trigger

In this conceptual example, a malicious VHDX file is created and mounted to a target directory. The ‘trigger’ file within the mounted disk is then read, causing the system to over-read the buffer, which can lead to the execution of the malicious payload embedded within the VHDX file.

Mitigation Guidance

The recommended mitigation for this vulnerability is to apply the vendor-supplied patch as soon as possible. In cases where immediate patching is not feasible, temporary mitigation can be achieved by deploying a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to detect and block attempts to exploit this vulnerability. Also, limit access to VHDX files to trusted users only and regularly monitor system logs for any unusual activity.
Remember, staying updated about such vulnerabilities and taking timely action is the cornerstone of effective cybersecurity management.