Vulnerability in Microsoft .Net Framework 3.5
CVE-2026-23666
Improper input validation in .NET Framework allows an unauthorized attacker to deny service over a network.
EPSS: 0.001 (31.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Microsoft .Net Framework 3.5 — versions 3.5.0
- Microsoft .Net Framework 3.5 And 4.7.2 — versions 4.7.0
- Microsoft .Net Framework 3.5 And 4.8 — versions 4.8.0
- Microsoft .Net Framework 3.5 And 4.8.1 — versions 4.8.1
- Microsoft .Net Framework 4.6.2/4.7/4.7.1/4.7.2 — versions 4.7.0
- Microsoft .Net Framework 4.8 — versions 4.8.0
- Microsoft .Net_framework — versions 3.5, 4.7.2, 4.8
- Microsoft Windows_10_1607
- Microsoft Windows_10_1809
- Microsoft Windows_10_21h2
Weakness classification (CWE)
References
- .NET Framework Denial of Service Vulnerability (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-23666?
- CVE-2026-23666 is a high-severity vulnerability in Microsoft .Net Framework 3.5, classified under Improper Handling of Exceptional Conditions. CVSS score: 7.5/10. Published 2026-04-14.
- How severe is CVE-2026-23666?
- High severity. CVSS v3 base score is 7.5 out of 10.