Microsoft has acknowledged issues related to the December 2025 security updates affecting Message Queuing (MSMQ) functionality on Windows 10 22H2, Windows Server 2019, and Windows Server 2016 systems. The updates KB5071546, KB5071544, and KB5071543 have caused problems such as inactive MSMQ queues, IIS sites showing “insufficient resources” errors, and applications unable to write messages to queues. These issues stem from modifications in the MSMQ security model, which now requires users to have write access to the C:WindowsSystem32msmqstorage folder, a privilege typically reserved for administrators. Systems with full administrative rights do not experience these problems, but this workaround is impractical for many enterprises. Microsoft is investigating the situation without a specified timeline for a resolution. Administrators may consider rolling back the updates, which poses its own security risks. In April 2023, Microsoft had warned about a critical vulnerability in MSMQ (CVE-2023-21554) that risked remote code execution attacks.