December Patch Tuesday Focuses on Zero-Day Risks and Fewer Fixes
391This December’s Patch Tuesday from Microsoft brings some important updates, mainly addressing three zero-day vulnerabilities. Surprisingly, the total number of patches is quite low this month, with only 57 updates released. Notably, no critical updates have been issued for the Windows platform this time, but the zero-day threats mean organizations should act quickly to patch their systems.
Zero-Day Vulnerabilities and Urgent Recommendations
The three zero-day flaws identified this month are CVE-2025-64671, CVE-2025-54100, and CVE-2025-62221. Zero-days are vulnerabilities that hackers can exploit before developers have a chance to fix them. Because of these serious risks, experts recommend applying patches immediately for Windows and Microsoft Office, even though few other updates are included this month.
While there are no updates for developer tools, Microsoft did release a minor patch for Microsoft Exchange Server. To help IT teams understand the risks and prioritize their patching strategies, Readiness has created an infographic detailing the potential impacts of these updates across different platforms.
Known Issues and Workarounds for December
Microsoft has published an unusually long list of known issues for this month’s updates. One notable problem affects Windows Server Update Services (WSUS). After installing certain updates, WSUS may stop showing detailed synchronization errors, which can complicate troubleshooting. This issue is related to addressing the CVE-2025-59287 remote code execution vulnerability.
Another minor issue involves the Windows login screen. Some users might notice that the password icon is missing, a bug that has persisted since the August 2025 update. Microsoft has provided a rollback option for most users, while enterprise deployments can use group policies to reset the icon’s appearance. Additionally, an out-of-band update for Windows Server 2025 temporarily halted Hotpatch updates for some machines. These will resume in the next baseline release expected in January 2026.
Revisions and Mitigations for Previous Fixes
This month also saw revisions to some earlier patches, mostly related to security and browser updates. Two updates stand out: one for a cryptographic vulnerability (CVE-2024-30098) that could have caused smart-card authentication issues, and another for a privilege escalation flaw (CVE-2025-60710) affecting Windows tasks.
Microsoft has clarified the details for these updates and provided guidance on how to detect and fix related problems. For the cryptographic issue, users who experienced authentication failures since October can reference KB5073121 for troubleshooting. For the privilege escalation vulnerability, Microsoft recommends disabling certain features before applying the patch, to ensure a smooth update process.
Overall, while this month’s patching cycle is lighter than usual, the presence of zero-day vulnerabilities makes timely updates especially critical. Organizations should review the known issues and plan their patch deployments carefully to maintain security and stability across their systems.
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