Patch tracker / KB5055515

KB5055515: Windows Server 2019 Security Update (April 2025)

KB5055515 is a High security update for Windows Server 2019, released 2025-04-08. It closes 1 CVE with a maximum CVSS of 8.6. The most likely of them to be attacked is CVE-2025-27737, which FIRST.org rates at 14% probability of exploitation in the next 30 days.

Update summary

High
2025-04-08
Released
1
CVEs fixed
8.6
Max CVSS
High
Severity
Deploy this cycle
Fixes 1 CVE for Windows Server 2019. No confirmed in-the-wild exploitation in this set today.

Fixes 1 CVE. Most severe CVSS 8.6 (High). EPSS exploit probability up to <1%. Among the lower half of tracked Microsoft updates by EPSS exploit probability.

Senserva found thiswe track every release for this product line, so we can tell you this package is behind

A newer security update for Windows 10 Version 1809 for 32-bit Systems has shipped since this one: KB5094041 (2026-08-11). 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.

Microsoft Update Catalog: download KB5055515Microsoft support article
Senserva AI Opinion for KB5055515

KB5055515 fixes CVE-2025-27737, a High severity flaw scoring 8.6 CVSS, one of the higher scores in this batch, affecting Windows 10 version 1809 and Windows Server 2019. These are older, long support platforms that are frequently still running in production, so this update deserves attention even without a confirmed KEV listing.

Do this: Prioritize KB5055515 on remaining Windows 10 1809 and Windows Server 2019 systems given its 8.6 CVSS score.

AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for KB5055515

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

Full tracking and change history for KB5055515

Released
2025-04-08
Last changed
2025-04-08
Changes tracked
1

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.

Check if KB5055515 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.

CVESeverityCVSSEPSSExploited
CVE-2025-27737High8.614%No

Scope and sources

Affected products
Also released in April 2025

KB5055518

59 CVEs · High · exploited

KB5055519

73 CVEs · High · exploited

KB5055521

60 CVEs · High · exploited

KB5055523

82 CVEs · High · exploited

KB5055526

77 CVEs · High · exploited

KB5055527

73 CVEs · High · exploited

KB5055528

65 CVEs · High · exploited

KB5055547

43 CVEs · High · exploited

The full month, summarized: Microsoft Patch Tuesday.

Authoritative references
Official KB5055515 page (Microsoft Support)Microsoft Update CatalogMicrosoft Security Update Guide

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

New to a term on this page? CVE, KB, KEV, CVSS, and EPSS are each explained once, on the Senserva security lexicon. Reference: Microsoft CVE and vulnerability management and the Microsoft patching guide.
Provided as is, without warranty; verify against the vendor advisory before acting. Data notice and terms.