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No exploitation reported

CVE-2026-23666

No exploitation reported by the sources we read.

  • Published2026-04-14
  • WeaknessCWE-366 · CWE-755

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Improper input validation in .NET Framework allows an unauthorized attacker to deny service over a network.

Timeline

dates in UTC
  1. 2026-04-1418:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-23666?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-23666?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Microsoft .net frameworkversion to verify
BranchAffectedFixed in
3.5= 3.5no fix published
4.7= 4.7.2no fix published
4.8= 4.8no fix published
4.8= 4.8.1no fix published
4.6= 4.6.2no fix published
4.7= 4.7no fix published
4.7= 4.7.1no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2026-23666 Red Hat Product Security

    dotnet: .NET Framework: Denial of Service via Race Condition

Full record on NVD

Fix

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2026-04-14
Last Modified
2026-07-15
NVD status
Modified
MSRC Title
.NET Framework Denial of Service Vulnerability

Frequently asked questions

What is CVE-2026-23666?

Improper input validation in .NET Framework allows an unauthorized attacker to deny service over a network.

Is CVE-2026-23666 actively exploited?

Active exploitation of CVE-2026-23666 has not been confirmed. Its EPSS score was 1.3% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-23666?

CVE-2026-23666 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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