CVE-2026-70580 in Windows
Summary
by MITRE • 10/14/2026
Missing authentication for critical function in Windows Credential Guard allows an authorized attacker to perform spoofing locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified as missing authentication for a critical function within the Microsoft Windows Credential Guard subsystem represents a significant security flaw that undermines one of the operating system's primary defenses against credential theft. Credential Guard is designed to isolate and protect sensitive credentials, such as NTLM hashes and Kerberos tickets, using hardware-based isolation features like Intel Virtualization-Based Security or AMD Secure Memory Encryption. By failing to enforce proper authentication checks for specific internal functions exposed by this subsystem, an attacker who has already gained local access can bypass these protections. This architectural weakness allows the malicious actor to interact directly with protected memory regions without triggering the necessary security validations that would normally prevent unauthorized access.
From a technical perspective, the core issue lies in the insufficient validation of caller privileges before executing sensitive operations within the Credential Guard service. While standard user-level applications are typically restricted from accessing kernel-mode structures or hardware-isolated memories, this specific flaw allows an authorized local attacker to invoke functions that should require higher integrity levels or explicit authentication tokens. The absence of these checks effectively neutralizes the isolation boundary intended by Virtualization-Based Security, enabling the attacker to read or manipulate protected credentials as if they possessed administrative privileges with full trust level access to the secure environment.
The operational impact of this vulnerability is severe, particularly in enterprise environments where Credential Guard is deployed to mitigate pass-the-hash and pass-the-ticket attacks. An authorized local attacker can exploit this flaw to perform credential spoofing locally, extracting plaintext passwords or cryptographic keys from memory. This capability allows for lateral movement across the network, as stolen credentials can be used to authenticate against other systems without detection by traditional security monitoring tools that rely on standard authentication logs. The attack does not require physical access or remote exploitation vectors, making it a critical risk for any system where local user accounts exist and Credential Guard is active but improperly configured or patched.
This flaw aligns with CWE-287, which describes Improper Authentication, specifically in the context of insufficient verification of identity before performing security-critical operations. It also maps to MITRE ATT&CK technique T1003, OS Credential Dumping, as it facilitates the extraction of sensitive authentication material from the operating system memory. Furthermore, it relates to T1558, Steal or Forge Kerberos Tickets, since the isolation breach allows access to cached Kerberos tickets that can be replayed for unauthorized network access.
Mitigation strategies must focus on applying vendor-provided security updates that patch the specific authentication checks within the Credential Guard service components. Organizations should ensure that all systems are running the latest cumulative updates from Microsoft, which address these validation gaps in the kernel and hypervisor interfaces. Additionally, administrators should verify that hardware virtualization extensions such as VT-x or AMD-V are enabled in the BIOS/UEFI settings to maintain the integrity of the isolation environment. Implementing strict local account policies and monitoring for unusual memory access patterns can also help detect attempts to exploit this vulnerability before significant damage occurs. Regular auditing of system logs for anomalies related to credential manager services is recommended to identify potential exploitation activities early.