CVE-2026-45498: Microsoft Defender Denial of Service Vulnerability
CVE-2026-45498 is a Severity not scored in source feed flaw in Microsoft Defender. Microsoft Defender contains an unspecified vulnerability that allows for denial of service. It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-05-20), meaning it is being actively exploited. The fix: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Source: CISA Known Exploited Vulnerabilities Catalog. Data as of 2026-06-13.
Vulnerability details
| Field | Value |
|---|---|
| CVE ID | CVE-2026-45498 |
| Vulnerability | Microsoft Defender Denial of Service Vulnerability |
| Vendor / product | Microsoft — Defender |
| CVSS base score | Not in source feed |
| Severity | — |
| Weakness (CWE) | — |
| Added to CISA KEV | 2026-05-20 |
| CISA remediation due | 2026-06-03 |
| Known ransomware use | Unknown |
Source: CISA Known Exploited Vulnerabilities Catalog. Data as of 2026-06-13.
What is the risk?
Microsoft Defender contains an unspecified vulnerability that allows for denial of service.
How to remediate CVE-2026-45498
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
U.S. federal civilian agencies were required to remediate this vulnerability by 2026-06-03 under CISA Binding Operational Directive 22-01. Private organizations should treat it with comparable urgency.
References
Frequently asked questions
What is CVE-2026-45498?
CVE-2026-45498 is a vulnerability in Microsoft Defender: Microsoft Defender contains an unspecified vulnerability that allows for denial of service.
How severe is CVE-2026-45498?
The CISA KEV catalog does not publish a CVSS base score for this entry. Check the NVD record for the official score. Its presence in the KEV catalog means it is confirmed to be exploited in the wild.
Is CVE-2026-45498 being exploited in the wild?
Yes. It appears in the CISA Known Exploited Vulnerabilities (KEV) catalog, which only lists vulnerabilities with reliable evidence of active exploitation. It was added on 2026-05-20.
How do I fix CVE-2026-45498?
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Related vulnerabilities
Last updated: 2026-06-13