Patch tracker / KB5055547
KB5055547: Windows 10 Security Update (April 2025)
KB5055547 is a High security update for Windows 10, released 2025-04-08. It closes 43 CVEs with a maximum CVSS of 8.8. At least one of them is actively exploited (CISA KEV) and linked to ransomware, so this is a deploy-first update. The most likely of them to be attacked is CVE-2025-26663, which FIRST.org rates at 14% probability of exploitation in the next 30 days.
Our data comes from Microsoft, CISA and other public sources, and it can be wrong or out of date. If you are unsure, check the linked source before you act, and tell us when we are wrong so we can fix it.
Update summary
Fixes 43 CVEs. At least one is actively exploited (CISA KEV). Most severe CVSS 8.8 (High). EPSS exploit probability up to 14%. One is linked to ransomware. Among the top half of tracked Microsoft updates by EPSS exploit probability.
A newer security update for Windows 10 for 32-bit Systems has shipped since this one: KB5066837 (2025-10-14). For cumulative update families the newer package includes these fixes, so installing that one is usually the shorter path. Verify against your own update rings before you skip this package.
We checked Microsoft's support article for KB5055547 on 2026-10-15 and it lists no known issues. Read the article before broad deployment; Microsoft adds issues as reports come in, and we re-check on every refresh.
KB5055547 is a smaller April 2025 package at 45 CVEs for Windows 10 1809 and Windows Server 2019, still High severity, CVSS 8.8, 18 percent EPSS, carrying the same CISA KEV listing and ransomware linkage as the rest of this month's family. Smaller CVE count here likely means a narrower servicing branch, not a lower-risk one, since the ransomware association applies to the shared core CVEs it still contains. Verify it against a broader sibling before assuming completeness.
Do this: Confirm KB5055547 closes the ransomware-linked CVEs shared with the larger April 2025 builds before treating any host running it as fully remediated.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5055547
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5055547
- Released
- 2025-04-08
- Last changed
- 2026-09-30
- Changes tracked
- 7
Senserva began recording day-to-day change history on 2026-07-07, and refreshes it several times a day. Release dates are historical where Microsoft publishes them; revision history is tracked from that date forward, so it does not include changes made before then.
Microsoft revised KB5055547 on 2026-09-30: CVEs fixed 45 to 43.
- 2026-08-07 CVEs fixed 45 to 43
- 2026-09-29 CVEs fixed 43 to 45
- 2026-09-30 CVEs fixed 45 to 43
Recorded by Senserva on the dates shown, from the MSRC release feed. This is what moved and when, which neither the vendor advisory nor NVD publishes.
Check if KB5055547 is installed
Elevated PowerShell. No output means it is not installed.
CVEs fixed by this update
Sorted exploited-first, then by CVSS. Every CVE links to its Senserva page with the full risk facts, references, and a ready-to-paste AI prompt.
Scope and sources
- Affected products
- Also released in April 2025
KB5055518
59 CVEs · High · exploitedKB5055519
73 CVEs · High · exploitedKB5055521
60 CVEs · High · exploitedKB5055523
82 CVEs · High · exploitedKB5055526
77 CVEs · High · exploitedKB5055527
73 CVEs · High · exploitedKB5055528
65 CVEs · High · exploitedKB5055557
55 CVEs · High · exploitedThe full month, summarized: Microsoft Patch Tuesday.
- Authoritative references
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.