Vulnerability · Published Apr 14, 2026 · Assigned by microsoft
CVE-2026-23666.NET Framework Denial of Service Vulnerability
High 7.5
In plain English
A high-severity security flaw in Microsoft .NET Framework 3.5 from Microsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.3% (higher than 71% of all known vulnerabilities).
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)1.3%top 28.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Improper input validation in .NET Framework allows an unauthorized attacker to deny service over a network.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Microsoft .NET Framework 3.5 | 3.5.0 – before 2.0.50727.8982 & 3.0.30729.8976 |
| Microsoft | Microsoft .NET Framework 3.5 AND 4.7.2 | 4.7.0 – before 2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0 |
| Microsoft | Microsoft .NET Framework 3.5 AND 4.8 | 4.8.0 – before 2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0 |
| Microsoft | Microsoft .NET Framework 3.5 AND 4.8.1 | 4.8.1 – before 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 | 4.7.0 – before 4.8.4801.0 |
| Microsoft | Microsoft .NET Framework 4.8 | 4.8.0 – before 4.8.4801.0 |
Weakness: CWE-755, CWE-366 · Vector: 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
References
- .NET Framework Denial of Service Vulnerability vendor-advisory, patch
- https://access.redhat.com/security/cve/CVE-2026-23666 vdb-entry, x_refsource_REDHAT
- RHBZ#2458271 issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23666.json x_sadp-csaf-vex