Windows Cryptographic Services Security Feature Bypass Vulnerability

Are there any further actions I need to take to be protected from this vulnerability? Yes. The Windows Smart Card infrastructure relies on the Cryptographic Service Provider (CSP) and Key Storage Provider (KSP) to isolate cryptographic operations from the Smart Card implementation. The KSP is part of the Crypto Next Generation (CNG) architecture and is intended to support modern smart cards. In the case of RSA based certificates, the Smart Card Certificate Propagation service automatically overrides the default and uses the CSP instead of the KSP. This limits usage to the cryptography provided by the CSP and does not benefit from the modern cryptography provided by the KSP. IMPORTANT REMINDER: The DisableCapiOverrideForRSA registry key will be removed. UPDATE February 10, 2026: Based on feedback from customers and software vendors, Microsoft is extending the removal date for the DisableCapiOverrideForRSA registry key from April 2026 to February 9, 2027.. This extension provides additional time to develop, test, and update applications that rely on the previous CSP-based behavior. The security fix remains enabled by default. UPDATE December 9, 2025: The October 14, 2025, Windows updates addressing CVE-2024-30098 revealed issues in applications where the code does not correctly identify which provider is managing the key for certificates propagated from a smart card to the certificate store. This misidentification can cause cryptographic operations to fail in certain scenarios. Please see Guidance for certificate handling for Smart Card propagated certificates for guidance for application developers on how to detect the correct handler and resolve these issues. UPDATE October 14, 2025: Starting with the October 2025 security updates, the fix will be enabled by default (DisableCapiOverrideForRSA set to 1) and the KSP will be used for RSA based certificates in the Smart Card Certificate Propagation service. If you discover applications relying on the old behavior, the DisableCapiOverrideForRSA registry key can be set back to 0 to switch back to auditing mode. The DisableCapiOverrideForRSA registry key will be removed in April 2026. UPDATE March 11, 2025: Starting with the security updates released on April 2025, the fix will automatically generate an audit event in cases where the Cryptographic Service Provider (CSP) is being used with RSA keys. If you have not already enabled the fix using the DisableCapiOverrideForRSA setting, you should monitor your systems for any error events in the Windows system event log. The Windows System event will include text that says: Event ID Event Type Text 624 Error Audit: This system is using CAPI for RSA cryptography operations. Please refer to the following link for more detail: https://go.microsoft.com/fwlink/?linkid=2300823 Note: when you enable the DisableCapiOverrideForRSA setting, auditing will stop. Beginning with the July 2024 security updates released on July 9, 2024, this vulnerability will be addressed by removing the RSA override and using the KSP as the default. This change is initially disabled by default to allow customers to test it in their environment and to detect any application compatibility issues that might occur with this change. Please enable this fix and test applications in your environment that rely on RSA based certificates and smart cards. If you detect applications that rely on the old behavior of defaulting to the CSP, work with your application vendor to update the application so that the KSP can be used by default. The fix can be enabled by setting the following registry key. Set the registry key to the value 1 to enable the fix for CVE-2024-30098. Registry Subkey HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography\Calais Key Value name DisableCapiOverrideForRSA Data Type REG_DWORD Data Set to 1 to enable the fix for CVE-2024-30098 and set to 0 or remove the key to disable the fix.

According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability? Successful exploitation of this vulnerability requires an attacker to create a SHA1 hash collision successfully.

What kind of security feature could be bypassed by successfully exploiting this vulnerability? An attacker who successfully exploited this vulnerability could bypass digital signatures on a vulnerable system.