CVE-2026-27908 Use-After-Free in Windows TDI Translation Driver

CVE-2026-27908 is a use-after-free vulnerability affecting the Windows TDI Translation Driver (tdx.sys). This flaw allows an attacker with local access and low privileges to escalate their privileges on the system. The vulnerability arises from improper memory management within the tdx.sys driver. Exploitation of this issue could allow the attacker to execute arbitrary code with elevated privileges. This vulnerability was published on April 14, 2026, and is documented by Microsoft as part of their regular security updates. Successful exploitation grants the attacker greater control over the compromised system and may facilitate further malicious activities.

Attack Chain

1. The attacker gains initial access to the target system with low privileges.
2. The attacker crafts a malicious program to interact with the TDI Translation Driver (tdx.sys).
3. The malicious program triggers the use-after-free condition within tdx.sys by freeing a memory object and then attempting to access it again.
4. The vulnerable driver attempts to access the freed memory, leading to a controlled memory corruption.
5. The attacker leverages the memory corruption to overwrite critical system data structures.
6. The attacker manipulates privilege-related fields in the overwritten data structures.
7. The attacker executes code that leverages the modified privilege levels.
8. The attacker successfully elevates their privileges to SYSTEM.

Impact

Successful exploitation of CVE-2026-27908 allows a local attacker to elevate privileges to SYSTEM. This gives the attacker complete control over the affected system, allowing them to install programs; view, change, or delete data; or create new accounts with full user rights. The vulnerability impacts any Windows system where the TDI Translation Driver is enabled. This privilege escalation could be a stepping stone for more extensive attacks within a corporate network.

Recommendation

• Apply the security update provided by Microsoft to patch CVE-2026-27908 as soon as possible. The update is available via https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-27908.
• Monitor process creation events for unusual processes being launched by system processes, which may indicate successful privilege escalation (see example Sigma rule).
• Consider disabling the TDI Translation Driver if it is not essential for system functionality. However, thoroughly test the impact of disabling this driver before implementing in a production environment.