Microsoft closed out 2025’s Patch Tuesday with a focused roll of updates: 57 vulnerabilities patched across Windows and related products, and at least one actively exploited zero‑day included in the mix.
What landed today
Among the fixes was an actively exploited Windows zero‑day tracked as CVE‑2025‑62221, a use‑after‑free bug in the Windows Cloud Files Mini Filter Driver that Microsoft rated serious (CVSS ~7.8) and which the Cybersecurity and Infrastructure Security Agency (CISA) has added to its Known Exploited Vulnerabilities catalog. Microsoft’s official Security Response Center has the full list of addressed issues and guidance for administrators at msrc.microsoft.com.
Different outlets parsed the release slightly differently — some counted multiple zero‑days or highly notable edge cases — but the consistent headline is the same: 57 CVEs patched, several high‑severity bugs called out as more likely to see exploitation, and no Critical severity bulletins this month.
Why this matters now
Two threads make this month’s release consequential. First, 2025 saw a large volume of Microsoft fixes overall, and this December set the year’s tally near 1,139 Microsoft CVEs — one of the busiest years on record for the vendor. Second, the security landscape keeps nudging administrators to be cautious about older, end‑of‑life software: November brought the debut of Windows 10 Extended Security Updates (ESU) and an exploited kernel elevation bug, so teams still running legacy images can’t treat updates as optional.
Help Net Security’s roundup also highlighted how AI is creeping into product tooling and patching workflows — an influence that will likely shape 2026 releases — and Microsoft’s recent hotpatch and preview fixes (including work on XAML‑dependent apps) show how complex the update matrix has become for enterprises.
Notable vulnerabilities called out
- CVE‑2025‑62221 — Use‑after‑free in the Windows Cloud Files Mini Filter Driver (actively exploited). CISA added it to the KEV catalog.
- A handful of high‑severity bugs affecting file systems and kernel components (examples mentioned in vendor notes and analyst coverage include issues in Win32K, the Common Log File System Driver, and Windows Resilient File System).
- Apply vendor updates in test rings before broad deployment to catch regressions — earlier in the year Microsoft had to ship an out‑of‑band fix after a hotpatch caused repeated downloads on Windows 11 devices.
- Treat the actively exploited zero‑day as urgent; if you can’t patch immediately, implement mitigations and network controls to reduce exposure.
- Watch for related side effects — recent XAML app fixes and Excel/Outlook attachment issues show that patches can sometimes ripple into user‑facing behavior.
Microsoft also flagged six vulnerabilities this month as more likely to be exploited in the wild; admins should treat those with extra priority. The full, canonical list and CVSS details are on Microsoft’s Security Response Center: https://msrc.microsoft.com.
What IT teams should do first
Patch quickly but cautiously. Priorities:
If you manage Windows 11 devices and are looking to quiet down unwanted UI noise after recent updates, our guide on cleaning up Windows 11 25H2 may help you tidy settings and reduce distractions: clean up Windows 11 25H2. And if your estate still remembers the October BitLocker recovery headaches, be sure to test updates in a representative lab before broad rollout: BitLocker recovery warning.
Wider ecosystem notes
This Patch Tuesday wasn’t just Microsoft: Adobe also shipped a large set of fixes this cycle, addressing dozens (nearly 140 in some reports) of product vulnerabilities — another reminder that third‑party app patching must run alongside OS patch campaigns. For teams tracking how AI changes the vendor landscape, Microsoft’s recent MAI image model release and other AI moves are beginning to shape product roadmaps and, eventually, the types of bugs we see: Microsoft Unveils MAI‑Image‑1.
A practical closing thought (not a summary)
December’s release is a reminder that “quiet month” is a myth in modern IT. Even when there aren’t Critical kernels to stampede everyone into action, quietly exploited zero‑days and high‑severity kernel or driver bugs can be the lever attackers use to escalate an intrusion. Keep a tight testing cadence, prioritize known‑exploited issues, and coordinate patching with your backup and recovery playbooks so fixes don’t inadvertently become problems of their own.
For authoritative details on each CVE and Microsoft’s supplied mitigations, consult Microsoft’s Security Response Center at https://msrc.microsoft.com and CISA’s KEV catalog at https://www.cisa.gov/known-exploited-vulnerabilities-catalog.