High severity · published May 20, 2026
CVE-2026-45584
Microsoft Defender Remote Code Execution Vulnerability
8.1
CVSS
0.9%
EPSS
No
On KEV
Description
Heap-based buffer overflow in Microsoft Defender allows an unauthorized attacker to execute code over a network.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.9% · higher than 58% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MM
Microsoft Malware Protection Engine · Microsoft
1.1.0.0 before 1.1.26040.8 · source: vendor
MP
Malware Protection Engine · Microsoft
1.1.26030.3008 before 1.1.26040.8 · source: NVD
Affected product
MM
Microsoft Malware Protection Engine
Microsoft
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-45584
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-45584
Vendor Advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45584
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