CVEs / CVE-2026-45498
CVE-2026-45498: Microsoft Defender Denial of Service Vulnerability
- Known exploited in the CISA KEV catalog since 20 May 2026
- high 7.5 CVSS 3.1 (NVD)
- EPSS 63% chance of exploitation in the next 30 days, higher than 99% of CVEs (30 Oct 2026)
- Last changed at its sources
Are you affected? Check your servers with Stackurity: it lists the software on each server and the vulnerabilities to fix first.
Check your servers with Stackurity Already using Stackurity? Search for CVE-2026-45498
Summary
Microsoft Defender contains an unspecified vulnerability that allows for denial of service.
Description
Microsoft Defender Denial of Service Vulnerability
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Microsoft Microsoft Defender Antimalware Platform | from 4.0.0.0, before 4.18.26040.7 | 4.18.26040.7 |
Exploitation
| In CISA KEV since | 20 May 2026 |
|---|---|
| Due date for US federal agencies | 3 Jun 2026 |
| Used in ransomware campaigns | Unknown |
| 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. |
Severity
| CVSS 3.1 | 7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HScored by NVD |
|---|---|
| Weakness | CWE-400 |
References
- CVE-2026-45498 on NVD
- CVE-2026-45498 in the CISA KEV catalog
- https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-45498 (cited by CISA)
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45498 Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-45498 Third Party Advisory, US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.