The Windows Transport Driver Interface (TDI) Translation Driver, known as TDX.sys, has been identified with a critical vulnerability labeled CVE-2025-49658. This flaw permits authorized local attackers to perform out-of-bounds read operations, potentially leading to the disclosure of sensitive information.
Understanding the Vulnerability
CVE-2025-49658 is an information disclosure vulnerability within the TDX.sys driver, a component integral to the Windows operating system's network stack. The vulnerability arises from improper handling of memory boundaries, allowing an attacker with local access to read beyond the allocated memory buffers. This can result in the exposure of sensitive kernel information, which could be leveraged for further attacks.
Technical Details
The core issue lies in the TDX.sys driver's failure to properly validate input lengths during memory operations. Specifically, when processing certain requests, the driver does not adequately check the size of the data being handled, leading to out-of-bounds read operations. This oversight can allow an attacker to access areas of memory that should be restricted, potentially revealing critical system information.
Potential Impact
While this vulnerability does not allow for remote exploitation, it poses a significant risk in scenarios where an attacker has local access to the system. By exploiting this flaw, an attacker could gain insights into the system's memory layout, kernel addresses, or other sensitive information. Such information is invaluable for crafting further exploits, particularly those aimed at privilege escalation or bypassing security mechanisms like Address Space Layout Randomization (ASLR).
Mitigation Strategies
To address CVE-2025-49658, Microsoft has released a security update that rectifies the improper input validation in the TDX.sys driver. Users and administrators are strongly advised to apply this update promptly to mitigate the risk associated with this vulnerability.
In addition to applying the patch, the following best practices are recommended:
- Limit Local Access: Restrict physical and local access to systems, ensuring that only authorized personnel can interact with critical infrastructure.
- Monitor System Logs: Implement comprehensive logging and monitoring to detect unusual activities that may indicate exploitation attempts.
- Regular Security Audits: Conduct periodic security assessments to identify and remediate potential vulnerabilities within the system.
This is not the first time vulnerabilities have been identified in the TDX.sys driver. For instance, CVE-2017-0296 was an elevation of privilege vulnerability caused by the driver's failure to check buffer lengths before copying memory, allowing attackers to escalate privileges on affected systems.
Similarly, other components interacting with the TDI have faced vulnerabilities. The Ancillary Function Driver (AFD), which supports Windows sockets applications and interfaces with TDI transports, has had multiple elevation of privilege vulnerabilities due to improper input validation. Notable examples include CVE-2012-0149 and CVE-2014-1767, both of which allowed attackers to execute arbitrary code in kernel mode. (learn.microsoft.com, learn.microsoft.com)
Conclusion
The discovery of CVE-2025-49658 underscores the importance of rigorous input validation within kernel-mode drivers. While Microsoft has addressed this specific vulnerability through a security update, it serves as a reminder for organizations to maintain vigilant security practices, including timely patch management and adherence to the principle of least privilege. By staying proactive, users can mitigate the risks associated with such vulnerabilities and maintain the integrity of their systems.
Source: MSRC Security Update Guide - Microsoft Security Response Center
