Patch tracker / KB5049981
KB5049981: Windows Server 2019 Security Update (January 2025)
KB5049981 is a Critical security update for Windows Server 2019, released 2025-01-14. It closes 121 CVEs with a maximum CVSS of 9.8. At least one of them is actively exploited (CISA KEV), so this is a deploy-first update. The most likely of them to be attacked is CVE-2025-21411, which FIRST.org rates at 81% probability of exploitation in the next 30 days.
Update summary
Fixes 121 CVEs. At least one is actively exploited (CISA KEV). Most severe CVSS 9.8 (Critical). EPSS exploit probability up to 81%. Among the top 10% 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 1 known issue with this update.
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KB5049981 is January 2025's massive cumulative update for Windows 10 version 1809 and Windows Server 2019, closing one hundred twenty one CVEs in a single package, among them CVE-2025-21411 and CVE-2025-21413. The worst is rated Critical at CVSS 9.8, a score profile typical of a remotely exploitable bug needing no authentication, and it carries an 81 percent EPSS score alongside a CISA KEV listing, so exploitation is already happening. A CVE count this large means deferring the update leaves well over a hundred known holes open.
Do this: Schedule KB5049981 for immediate deployment across all Windows 10 1809 and Windows Server 2019 systems given its Critical rated, actively exploited top flaw.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for KB5049981
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5049981
- Released
- 2025-01-14
- Last changed
- 2025-01-14
- 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 KB5049981 is installed
Elevated PowerShell. No output means it is not installed.
Known issues, from Microsoft
Quoted from Microsoft's support article for KB5049981 (checked 2026-08-11). Verify against the article before acting.
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| Symptom
| Workaround
| Following the installation of the October 2024 security update, some customers report that the OpenSSH (Open Secure Shell) service fails to start, preventing SSH connections. The service fails with no detailed logging, and manual intervention is required to run the sshd.exe process.This issue is affecting both enterprise, IOT, and education customers, with a limited number of devices impacted. Microsoft is investigating whether consumer customers using Home or Pro editions of Windows are affected.
| This issue is addressed in KB5052077 .
| 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 ...
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 January 2025
KB5049984
128 CVEs · Critical · exploitedKB5050009
128 CVEs · Critical · exploitedKB5050021
121 CVEs · Critical · exploitedKB5049983
122 CVEs · CriticalKB5049993
112 CVEs · CriticalKB5050004
93 CVEs · CriticalKB5050006
71 CVEs · CriticalKB5050008
118 CVEs · CriticalThe full month, summarized: Microsoft Patch Tuesday.
- Authoritative references
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.