Patch tracker / KB5055526
KB5055526: Windows Server 2019 Security Update (April 2025)
KB5055526 is a High security update for Windows Server 2019, released 2025-04-08. It closes 80 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. Get it from the Microsoft Update Catalog below, and see where it sits against the rest of the month on the patch tracker.
Microsoft security update released 2025-04-08. Fixes 80 CVEs.
Exploitation is not theoretical here: at least one CVE this update fixes is on the CISA Known Exploited Vulnerabilities catalog, which means attackers are already using it against unpatched systems, including in ransomware campaigns. For an update like this, the risk window is the gap between today and the day your last device installs it, so shortening that gap matters more than perfect scheduling.
Most organizations deliver an update like this automatically through Intune update rings, Windows Update for Business, Windows Autopatch, or WSUS; the install section below covers each path, including how to expedite it for the exploited CVE. For the bigger picture: how the Microsoft patching tools fit together, this month's Patch Tuesday summary, and every update ranked by real-world risk.
Updated July 24, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Download KB5055526
Get the official update for KB5055526. The download and file size for each supported product are on the Microsoft Update Catalog page.
Update summary
Senserva AI Opinion for KB5055526
KB5055526 broadens April 2025's fix set to 80 CVEs for the same Windows 10 1809 and Server 2019 population, adding CVE-2025-26681 to the list while keeping the same High, CVSS 8.8 severity, 18 percent EPSS, ransomware linkage, and CISA KEV listing as KB5055519. Being one of the largest CVE counts in this entire batch of 100, it likely represents the most complete build for this branch. Given the ransomware tie, this is not one to defer.
Do this: Prefer KB5055526 as the most complete April 2025 build for this branch and deploy it on an emergency basis given the ransomware linkage.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5055526
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5055526
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.
Exploitation and severity
Fixes 80 CVEs. At least one is actively exploited (CISA KEV). Most severe CVSS 8.8 (High). EPSS exploit probability up to 13%. One is linked to ransomware.
Among the top half of tracked Microsoft updates by EPSS exploit probability.
What to do
Treat as urgent: it is being exploited in the wild (CISA KEV), so patch ahead of items that are not. Senserva flags whether KB5055526 is missing on your devices.
Check if KB5055526 is installed
Copy-paste PowerShell: one machine, or your whole fleet in one pass. No output means the update is not installed.
Get-HotFix covers Windows updates. Office, SharePoint, and Exchange server updates show under installed updates in Programs and Features, or check the Update Catalog history.
Known issues, from Microsoft
Quoted from Microsoft's support article for KB5055526 (checked 2026-07-21). Verify against the article before acting.
Citrix
Symptom
Workaround
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.
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 ".
System Guard Runtime Monitor Broker service
Symptom
Workaround
The Windows Event Viewer might display an error related to SgrmBroker.exe, on devices that have installed Windows updates ...
Writing about KB5055526? Cite this page
Copy-paste for a blog post, forum answer, or internal doc. The link always carries the current risk data.
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.
Affected products
Also released in April 2025
The highest-risk updates from the same release:
The full month, summarized: Microsoft Patch Tuesday.
How to install KB5055526
Any of these paths delivers KB5055526; most organizations already have one of the first three running:
- Intune update rings (Windows Update for Business): the update flows on each ring's deferral schedule. For this update, consider an expedite policy: it bypasses deferrals for exactly this fix-now case.
- Windows Autopatch: rings, rollout, and pause or rollback are managed for you; exploited updates can be expedited.
- WSUS / Configuration Manager: approve KB5055526 for your device groups and set a deadline (deadline, not just approval, for an exploited fix).
- Manual: download from the Update Catalog above and install; fine for a handful of machines, unmanageable at any real scale.
After the rollout, verify rather than assume: update compliance reporting in Intune or Autopatch shows which devices actually installed it, and Siemserva reads Intune, Defender, Autopatch, and Azure Update Manager together to show the devices still missing KB5055526, ranked by exploitation.
Common questions about KB5055526
Does KB5055526 have known issues?
Yes. Microsoft's support article documents known issues for KB5055526 (checked 2026-07-21). The Known issues section on this page quotes it; verify against the article before acting.
Is KB5055526 urgent?
Yes. KB5055526 fixes at least one vulnerability in the CISA Known Exploited Vulnerabilities catalog, meaning attackers are using it in the wild, including in ransomware campaigns. Deploy it first.
How do I download KB5055526?
From the Microsoft Update Catalog (linked on this page), or let Intune, Windows Update for Business, Windows Autopatch, or WSUS deliver it. The catalog page lists the download for each supported product.
How do I deploy KB5055526 with Intune?
Assign a Windows Update ring (quality update policy) to the device groups and the update flows on the ring's deferral schedule. Because KB5055526 fixes an actively exploited CVE, an Intune expedite policy is the right tool: it bypasses configured deferrals and pushes the update as soon as devices check in. Verify the rollout with update compliance reporting rather than assuming delivery.
Can I ask my own AI about KB5055526?
Yes. This page includes a free, ready-to-paste AI prompt containing KB5055526's key facts: severity, CVE count, exploitation status, and the download link. Copy it into Claude, ChatGPT, or Copilot for a rollout plan; the data is refreshed three times a day (5 AM, 12:30 PM, and 7 PM US Central).
Authoritative references
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.
