SB2026052119 - Denial of service in Microsoft Defender
Published: May 21, 2026
Security Bulletin ID
SB2026052119
CSH Severity
High
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Partial DoS
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Input validation error (CVE-ID: CVE-2026-45498) Exploited
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 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]
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.
Remediation
Install update from vendor's website.