CVE-2026-45498
Microsoft Defender Denial of Service Vulnerability
- Published
- Updated
- Reserved
- Assigned by
- microsoft
Description
Microsoft Defender Denial of Service Vulnerability
Exploited in the wild
CISA lists this vulnerability in its Known Exploited Vulnerabilities catalog as Microsoft Defender Denial of Service Vulnerability.
- Added
- 20 May 2026
- Fix due (US federal)
- 3 Jun 2026
- Used by ransomware
- Not known
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: it is being exploited.
Timeline
ID reserved
By microsoft
- 8 days later
· 8 days later
Published
Added to CISA KEV
Known exploited in the wild
- 3 months later
· 3 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| microsoftCNA (assigner) | 3.1 | Medium4.0 | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:U/RL:O/RC:C |
| NVDNVD · Analyzed | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 63.1% · top 0.8% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: active · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.0.
Weakness
Affected products
Microsoft · Microsoft Defender Antimalware Platform
- affected 4.0.0.0 – < 4.18.26040.7
References (2)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- CISA KEV catalog (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-45498)Record last updated .