Strongcertificatebindingenforcement ((install)) -

In security, "fallback to insecure" is just "insecure with extra steps."

Before you flip the switch to across all your DCs, you need to audit your environment. Switching to Enforced will break authentication for any user or device that relies on weak certificate mapping. strongcertificatebindingenforcement

If you are seeing authentication failures or Event ID 39 in your logs, you must take action immediately: In security, "fallback to insecure" is just "insecure

Note: Microsoft often rolls out these mitigations in phases. The default value might be 1 after installing a specific security update, but 2 is required for full protection. The default value might be 1 after installing

: Modify your Windows Enterprise CA templates to include the new SID extension.

Microsoft has deployed this change in phases to give administrators time to update their Public Key Infrastructure (PKI) and re-issue certificates. As of mid-2026, we are in the final stages of this rollout.

: Legacy behavior. Strongly discouraged and currently unsupported.