Actively exploited in the wild
Microsoft Defender Denial of Service Vulnerability
Microsoft - Defender · Listed in the CISA KEV since 2026-05-20. This indicates confirmed attacks in production environments.
Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CVE-2026-45498
MediumCVSS 4.0KEVExploitation Probability (EPSS)
Very high risk99th percentile - higher than 99% of all known CVEs
Summary
Microsoft Defender Denial of Service Vulnerability.
Risk Assessment
An attacker could cause the Defender service to crash or become unavailable, weakening system protection against malware.
Recommendation
Install the latest Microsoft Defender security updates.
Other vulnerabilities in Microsoft Defender
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Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.
- CVE-2026-33825HighActively exploited
Insufficient granularity of access control in Microsoft Defender allows an authorized attacker to elevate privileges locally.
- CVE-2021-42298High
Remote code execution vulnerability in Microsoft Defender. An attacker could exploit this vulnerability to execute arbitrary code on the system.
- CVE-2026-50658High
A Time-of-check time-of-use (TOCTOU) race condition in Microsoft Defender allows an authorized attacker to elevate privileges locally.
- CVE-2026-50657Medium
In Microsoft Defender, exposure of private personal information to an unauthorized actor allows an authorized attacker to disclose information locally.
- CVE-2026-55012High
An integer overflow or wraparound vulnerability has been discovered in Microsoft Defender. This flaw allows an unauthorized attacker to execute code locally.
- CVE-2026-55011High
An integer underflow (wrap or wraparound) vulnerability in Microsoft Defender allows an unauthorized attacker to execute code locally.
- CVE-2026-45584High
Heap-based buffer overflow in Microsoft Defender allows an unauthorized attacker to execute code over a network.
- CVE-2023-33156Medium
A vulnerability in Microsoft Defender allows for elevation of privilege, potentially leading to unauthorized access to the system.
- CVE-2021-34471High
Elevation of privilege vulnerability in Microsoft Defender. An attacker could exploit it to gain elevated privileges.
Original NVD description (English source)
Microsoft Defender Denial of Service Vulnerability