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CVE-2026-23666
.NET Framework Denial of Service Vulnerability
High7.5EPSS 1.3%
- Published
- Updated
- Reserved
- Assigned by
- microsoft
Description
Improper input validation in .NET Framework allows an unauthorized attacker to deny service over a network.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| microsoftCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C |
| redhat-SADPADP (enrichment) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Modified | 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)
- 1.3% · top 29% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Weakness
Affected products
Microsoft · Microsoft .NET Framework 3.5
- affected 3.5.0 – < 2.0.50727.8982 & 3.0.30729.8976
Microsoft · Microsoft .NET Framework 3.5 AND 4.7.2
- affected 4.7.0 – < 2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0
Microsoft · Microsoft .NET Framework 3.5 AND 4.8
- affected 4.8.0 – < 2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0
Microsoft · Microsoft .NET Framework 3.5 AND 4.8.1
- affected 4.8.1 – < 2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0
Microsoft · Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2
- affected 4.7.0 – < 4.8.4801.0
Microsoft · Microsoft .NET Framework 4.8
- affected 4.8.0 – < 4.8.4801.0
References (4)
- .NET Framework Denial of Service Vulnerability (opens in a new tab)vendor-advisorypatch
- https://access.redhat.com/security/cve/CVE-2026-23666 (opens in a new tab)vdb-entryx_refsource_REDHAT
- RHBZ#2458271 (opens in a new tab)issue-trackingx_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23666.json (opens in a new tab)x_sadp-csaf-vex
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)
- 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-2026-23666)Record last updated .