Microsoft Patches Actively Exploited Defender Vulnerabilities Affecting Enterprise Systems

**Microsoft Defender actively exploited vulnerabilities** — The report describes active in-the-wild exploitation of CVE-2026-41091 (local privilege escalation, CVSS 7.8) and CVE-2026-45498 (denial-of-service, CVSS 4.0), notes an additional patched RCE (CVE-2026-45584), references researcher observations and possible ties to previously disclosed issues (RedSun/UnDefend), and highlights CISA adding the actively exploited CVEs to its KEV catalog with mitigation guidance and automatic Defender updates.