CVE-2026-45498

Microsoft Defender: Denial of Service

As of , CVE-2026-45498 in Microsoft Defender is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch soon.

Exploited
Yes: CISA listed it on 20 May 2026
US federal deadline
3 June 202614 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
Not known to CISA
EPSS score
0.01Higher than 68% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
Public exploit
None foundNeither Metasploit nor Exploit-DB lists one.
Fix
Vendor advice: msrc.microsoft.comLinks below, from CISA's entry.

What CISA says to do

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

CISA's required action

What the flaw is

Microsoft Defender contains an unspecified vulnerability that allows for denial of service.

CISA's description

Microsoft Defender Denial of Service Vulnerability

The CVE record's description, from microsoft

CVE published
20 May 2026
Assigned by
microsoft
CVSS
4.0 Medium (CVSS 3.1, from the CNA)
CWE-400
Uncontrolled Resource Consumption
CISA SSVC, exploitation
active
CISA SSVC, automatable
no
CISA SSVC, technical impact
partial

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.

Defender: other exploited entries

VulnerabilityProductOur groupListedDeadlineEPSS
CVE-2026-33825Insufficient Granularity of Access ControlMicrosoft DefenderPatch nowRansomware use, listed within a year0.00
CVE-2022-44698SmartScreen Security Feature BypassMicrosoft DefenderPatch this weekRansomware use; EPSS 0.760.76
CVE-2021-1647Remote Code ExecutionMicrosoft DefenderPatch soon0.39
CVE-2026-41091Link FollowingMicrosoft DefenderPatch soon0.00

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