In this article Summary Take Action altSecID attributes Timeline of changes Registry Settings Audit Events Event ID: 45 Event ID: 21 Known issue Summary The Windows security updates released on or after April 8, 2025, contain protections for a vulnerability with Kerberos authentication. This update provides a change in behavior when the issuing authority of the certificate used for a security ...

Protect yourself from phishing Phishing (pronounced: fishing) is an attack that attempts to steal your money, or your identity, by getting you to reveal personal information -- such as credit card numbers, bank information, or passwords -- on websites that pretend to be legitimate. Cybercriminals typically pretend to be reputable companies, friends, or acquaintances in a fake message, which ...

Certificate authority (CA) A certificate authority is an entity similar to a notary public. It issues digital certificates, signs certificates to verify their validity and tracks which certificates have been revoked or have expired. Top of Page Digital signature assurances The following terms and definitions show what assurances are provided by digital signatures. Authenticity The signer is ...

How to manage Kerberos KDC usage of RC4 for service account ticket issuance changes related to CVE-2026-20833

If you tried to sign in with your Microsoft account and you received a message that said: "Your security info change is still pending" or "You can't access this site right now" It's because all the security info (such as alternate contact methods) that you previously added to your account was removed and replaced with new info. You need to wait 30-days for the changes to take effect.

Get security info and tips about threat prevention, detection, and troubleshooting. Including tech support scams, phishing, and malware.

Important: You don't need to remove old security information unless there is an account security risk (e.g. someone else has access to your old mailbox). If you do need to replace your security information, make sure you add new information first. If you request removal of all security information in your account, the account is put into a restricted state for 30-days. Your information doesn't ...

Learn how to identify and open encrypted and protected emails no matter what email client you're using.

Use the Information Protection viewer to view protected files in Windows, Android, iOS, or Edge.

If you see a message that says "Let's protect your account" or "Help us secure your account", it's because we need you to add some information to your account to verify that it's really you trying to sign in. We will ask for an email address or phone number that we can send a verification code to. It doesn't have to be your email or phone number - you just need to be able to access it to ...