Patch tracker / KB5055528
KB5055528: Windows Server 2019 Security Update (April 2025)
KB5055528 is a High security update for Windows Server 2019, released 2025-04-08. It closes 65 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.
Update summary
Fixes 65 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 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 documents 4 known issues with this update.
- Active Directory Group Policy: Events in local policy
- Windows 11, versions 24H2 might not download via Windows Server Updates Services
- Noto fonts issue
KB5055528 extends the narrower April 2025 fix set to 68 CVEs for Windows 10 1809 and Windows Server 2019, again High severity, CVSS 8.8, 18 percent EPSS, with the confirmed ransomware linkage and CISA KEV listing shared across this month's family. This is one of several overlapping April builds; what matters operationally is that every one of them carries the ransomware association, so none should be deprioritized. Confirm full CVE closure regardless of which specific KB a host received.
Do this: Confirm KB5055528 or an equivalent April 2025 build with full CVE coverage is applied, given the ransomware linkage running through this entire update family.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5055528
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5055528
- Released
- 2025-04-08
- Last changed
- 2026-08-12
- Changes tracked
- 4
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.
The strongest signal is the single revision on 2026-08-07, when the fixed CVE count was corrected downward from 68 to 65. With only one recorded change and no further movement, this reflects a minor adjustment rather than an escalating trend. For today, treat KB5055528 as stable and proceed with standard patch validation.
- 2026-08-07 CVEs fixed 68 to 65
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 KB5055528 is installed
Elevated PowerShell. No output means it is not installed.
Known issues, from Microsoft
Quoted from Microsoft's support article for KB5055528 (checked 2026-08-12). Verify against the article before acting.
Citrix
Applies to: All users
Symptom
Devices that have certain Citrix components installed might be unable to complete installation of the January 2025 Windows security update. This issue was observed on devices with Citrix Session Recording Agent (SRA) version 2411. The 2411 version of this application was released in December 2024.
Affected devices might initially download and apply the January 2025 Windows security update correctly, such as via the Windows Update page in Settings. However, when restarting the device to complete the update installation, an error message with text similar to “Something didn’t go as planned. No need to worry – undoing changes” appears. The device will then revert to the Windows updates previously present on the device.
This issue likely affects a limited number of organizations as version 2411 of the SRA application is a new version. Home users are not expected to be affected by this issue.
Workaround
The issue has been resolved in Citrix Session Recording Agent version 2503, released on April 28, 2025, and newer versions.
For details, see the documentation provided by Citrix at " Microsoft's January Security Update Fails/Reverts on a machine with 2411 Session Recording Agent ".
Active Directory Group Policy: Events in local policy
Symptom
Audit Logon/Logoff events in the local policy of the Active Directory Group Policy might not show as ...
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 · exploitedKB5055547
43 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.