CVE-2026-23666: microsoft microsoft .net framework 3.5
CVSS: 7.5v3.1HighModified
Published 14-04-2026Last modified 15-10-2026
Vulnerability summary
CVE-2026-23666 is a high (CVSS 7.5) vulnerability in microsoft microsoft .net framework 3.5. EPSS estimates a 1.33% chance of exploitation in the next 30 days, higher than 70.6% of scored vulnerabilities.
CVSS score
7.5/10
010
High · v3.1 (CVE.org)EPSS score
1.33%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Timeline
- 14-04-2026PublishedVulnerability first disclosed.
- 15-10-2026Last modifiedVulnerability information updated.
Description
Improper input validation in .NET Framework allows an unauthorized attacker to deny service over a network.
CVSS metrics
2 scores · 2 sources · 1 versionHigh 7.5Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:CSourcesAll 2 agree
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
1.33%
Chance of exploitation in the next 30 days
Percentile
71%
Versus all other CVEs
30-day change
0.00 pp
From 1.33% on 20-09-2026
20-09-202620-10-2026
EPSS score1.33%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-755Improper Handling of Exceptional ConditionsThe product does not handle or incorrectly handles an exceptional condition.
- CWE-366Race Condition within a ThreadIf two threads of execution use a resource simultaneously, there exists the possibility that resources may be used while invalid, in turn making the state of execution undefined.
Affected systems
Microsoft7 products
- microsoft .net framework 3.5≥ 3.5.0, < 2.0.50727.8982 & 3.0.30729.8976
- microsoft .net framework 3.5 and 4.7.2≥ 4.7.0, < 2.0.50727.9068 & 3.0.30729.9065 & 4.7.4141.0
- microsoft .net framework 3.5 and 4.8≥ 4.8.0, < 2.0.50727.9068 & 3.0.30729.9065 & 4.8.4801.0
- microsoft .net framework 3.5 and 4.8.1≥ 4.8.1, < 2.0.50727.9181 & 3.0.30729.9165 & 4.8.9332.0
- microsoft .net framework 4.6.2/4.7/4.7.1/4.7.2≥ 4.7.0, < 4.8.4801.0
1 vendor · 7 products
