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Microsoft Security Response CenterCVE-2026-45498

Microsoft Defender Denial of Service Vulnerability

References Identification Last version of the Microsoft Defender Antimalware Platform affected by this vulnerability 4.18.26030.3011 First version of the Microsoft Defender Antimalware Platform with this vulnerability addressed Version 4.18.26040.7 See Manage Updates Baselines Microsoft Defender Antivirus for more information. Microsoft Defender is disabled in my environment, why are vulnerability scanners showing that I am vulnerable to this issue? Vulnerability scanners are looking for specific binaries and version numbers on devices. Microsoft Defender files are still on disk even when disabled. Systems that have disabled Microsoft Defender are not in an exploitable state. Why is no action required to install this update? In response to a constantly changing threat landscape, Microsoft frequently updates malware definitions and the Windows Defender Antimalware Platform. In order to be effective in helping protect against new and prevalent threats, antimalware software must be kept up to date with these updates in a timely manner. For enterprise deployments as well as end users, the default configuration in Microsoft antimalware software helps ensure that malware definitions and the Windows Defender Antimalware Platform are kept up to date automatically. Product documentation also recommends that products are configured for automatic updating. Best practices recommend that customers regularly verify whether software distribution, such as the automatic deployment of Windows Defender Antimalware Platform updates and malware definitions, is working as expected in their environment. How often are the Microsoft Defender Antimalware Platform and malware definitions updated? Microsoft typically releases an update for the Microsoft Defender Antimalware Platform once a month or as needed to protect against new threats. Microsoft also typically updates the malware definitions three times daily and can increase the frequency when needed. Depending on which Microsoft antimalware software is used and how it is configured, the software may search for platform, engine and definition updates every day when connected to the Internet, up to multiple times daily. Customers can also choose to manually check for updates at any time. What is the Microsoft Defender Antimalware Platform? The Microsoft Defender Antimalware Platform is a collection of user-mode binaries (e.g. MsMpE

4.0CVSS out of 10Low severity
Scope

What the vendor says is affected

  • Microsoft Defender Antimalware Platform

Versions the vendor lists as fixed

  • 4.18.26040.7
Next step

What the vendor recommends

Release Notes

Review the complete instructions on the vendor's site
Timeline

When this advisory changed

  1. Published by Microsoft Security Response Center

    The publication date reported by the vendor.

  2. Updated by Microsoft Security Response Center

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  3. Added to SecurityAlert

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Vulnerabilities

CVEs named in this advisory