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Microsoft Releases Out-of-Band Update After Security Patch Causes Kerberos Issues

Microsoft has released an out-of-band update after learning that a recent Windows security patch started causing Kerberos authentication issues.

The Patch Tuesday updates released on November 8 addressed CVE-2022-37966, a privilege escalation vulnerability affecting Windows Server. This high-severity flaw can allow an attacker who can collect information about the targeted system to gain admin privileges.

“An unauthenticated attacker could conduct an attack that could leverage cryptographic protocol vulnerabilities in RFC 4757 (Kerberos encryption type RC4-HMAC-MD5) and MS-PAC (Privilege Attribute Certificate Data Structure specification) to bypass security features in a Windows AD environment,” Microsoft explained in its advisory for CVE-2022-37966.

However, a few days after the patch was released, users started complaining about issues related to Kerberos authentication.

Microsoft acted quickly and a few days later it provided mitigations. Then, on November 17, it released an out-of-band update that should address the issue.

“Customers who have not already installed the security updates released on November 8, 2022 should install the out-of-band updates instead. Customers who have already installed the November 8, 2022 Windows security updates and who are experiencing issues should install the out-of-band updates,” Microsoft told customers.

CVE-2022-37966 has not been exploited in the wild and it has not been publicly disclosed, but Microsoft has assigned it an ‘exploitation more likely’ rating.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.