Patch tracker / KB5063221

KB5063221

Microsoft security update released 2025-08-12. Fixes 4 CVEs.

High

Download KB5063221

Get the official update for KB5063221. The download and file size for each supported product are on the Microsoft Update Catalog page.

Microsoft Update Catalog: download KB5063221 Microsoft support article

Update summary

Released

2025-08-12

CVEs fixed

4

Max CVSS

7.5

Severity

High

Exploitation and severity

Fixes 4 CVEs. Most severe CVSS 7.5 (High). EPSS exploit probability up to 1.3%.

Among the lower half of tracked Microsoft updates by EPSS exploit probability.

What to do

Moderate priority: schedule it in your normal patch cycle. Senserva flags whether KB5063221 is missing on your devices.

CVEs fixed by this update

CVE-2025-25005 CVE-2025-25006 CVE-2025-25007 CVE-2025-33051

Affected products

Microsoft Exchange Server 2016 Cumulative Update 23
Microsoft Exchange Server 2019 Cumulative Update 14
Microsoft Exchange Server 2019 Cumulative Update 15

References

Microsoft support article Microsoft Security Update Guide

See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.

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Lexicon: the terms on this page

CVE: Common Vulnerabilities and Exposures. A unique ID for one publicly known vulnerability, such as CVE-2025-1234.
KB: Microsoft Knowledge Base article. The identifier for a specific Microsoft update.
KEV: CISA Known Exploited Vulnerabilities. CVEs confirmed exploited in the wild. Fix these first.
CVSS: Common Vulnerability Scoring System. A standardized Severity score from 0 to 10.
EPSS: Exploit Prediction Scoring System. The probability a CVE will be exploited in the next 30 days.
MSRC: Microsoft Security Response Center. Microsoft's Patch Tuesday advisories and KB-to-CVE mapping.
NVD: National Vulnerability Database (NIST). Authoritative CVE metadata and CVSS scores.
Ransomware: The vulnerability is linked to known ransomware activity.