Microsoft has just rolled out a non-secure urgent out-of-band (OOB) update (KB5020387) to fix an SSL/TLS handshake failure on some client and server platforms. On affected devices, users will see SEC_E_ILLEGAL_MESSAGE errors in the application when there is a connection problem to the server.
Microsoft explains, “We resolved issues that could affect certain types of Secure Sockets Layer (SSL) and Transport Layer Security (TLS) connections. These issues can cause handshake failures. For developers, affected connections may receive one or more records in a single input buffer, followed by a partial record less than 5 bytes in size.”
Known issues resolved in today’s OOB update affect multiple Windows versions and editions, including.
"Client:Windows 11, version 22H2; Windows 11, version 21H2; Windows 10, version 21H2; Windows 10, version 21H1; Windows 10, version 20H2; Windows 10 Enterprise LTSC 2019; Windows 10 Enterprise LTSC 2016; Windows 10 Enterprise 2015 LTSB; Windows 8.1; Windows 7 SP1 Servers: Windows Server 2022; Windows Server 2019; Windows Server 2016; Windows Server 2012 R2; Windows Server 2012; Windows Server 2008 R2 SP1"
This update cannot be deployed through Windows Update, Windows Update for Business or Windows Server Update Services (WSUS). Users can manually download through the Microsoft Update Catalog and then manually bring in to WSUS and Microsoft Endpoint Configuration Manager.
Microsoft has released standalone packages and cumulative updates
Cumulative Updates:
"● Windows 11, version 21H2: KB5020387 ● Windows Server 2022: KB5020436 ● Windows 10, version 20H2; Windows 10, version 21H1; Windows 10, version 22H1; Windows 10 Enterprise LTSC 2021: KB5020435 ● Windows 10 Enterprise LTSC 2019; Windows Server 2019: KB5020438"
Independent update:
"● Windows 8.1; Windows Server 2012 R2: KB5020447 ● Windows Server 2012: KB5020449 ● Windows 7 SP1; Windows Server 2008 R2 SP1: KB5020448"
