Input validation error in Windows Defender - CVE-2026-45498
Published: May 21, 2026
Vulnerability identifier: #VU132036
CSH Severity: High
CVSS v4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-45498
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
The vulnerability is being exploited in the wild
Vulnerability details
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can pass a specially crafted file to the application and temporary disable antimalware protection.
Note, the vulnerability is being actively exploited in the wild.
Affected software
Windows Defender
How to mitigate CVE-2026-45498
Install updates from vendor's website.
Windows Defender - update to 4.18.26040.7