# CVE-2026-23666: Microsoft .NET Framework denial of service via race condition

Source: https://junglewise.ai/threats/cve-2026-23666-microsoft-net-framework-denial-of-service-via-race-condition  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-14. Updated: 2026-06-30  
License: CC BY 4.0 with a link back

CVE-2026-23666 · Severity: high · CVSS 7.5 · Published 2026-04-14

A vulnerability in the Microsoft .NET Framework could allow an attacker to crash applications or services remotely. The .NET Framework is a widely used software platform for building and running Windows applications. An exploit could lead to a denial-of-service condition, disrupting business operations and making affected services unavailable to users.

Technologies: [Microsoft .NET Framework](https://junglewise.ai/threats/technologies/net-framework). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-23666 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-23666 being exploited in the wild.

**How severe is CVE-2026-23666?** High severity, with a CVSS score of 7.5, published 14 April 2026.

**Which products and versions are affected?** Microsoft .NET Framework < 2.0.50727.8982 & 3.0.30729.8976.

**Is there a fix for CVE-2026-23666?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-23666 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-23666?** Check whether you run Microsoft .NET Framework at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A denial-of-service vulnerability exists in the Microsoft .NET Framework due to improper input validation and a race condition (CWE-366) during concurrent execution using shared resources. The flaw is triggered when the framework improperly handles exceptional conditions (CWE-755) during network-based interactions. An unauthenticated attacker can exploit this over the network without user interaction to cause the affected application or service to become unresponsive or crash. Microsoft has released security updates to address this issue across various versions of .NET Framework on supported Windows and Windows Server platforms.

## Affected products

- Microsoft .NET Framework 3.5 < 2.0.50727.8982 & 3.0.30729.8976
- Microsoft .NET Framework 4.7.2 < 4.7.4141.0
- Microsoft .NET Framework 4.8 < 4.8.4801.0
- Microsoft .NET Framework 4.8.1 All versions on affected Windows platforms

## Timeline

- 2026-04-14: disclosed
- 2026-04-14: advisory

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-23666](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-23666)
- [https://access.redhat.com/security/cve/CVE-2026-23666](https://access.redhat.com/security/cve/CVE-2026-23666)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2458271](https://bugzilla.redhat.com/show_bug.cgi?id=2458271)
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23666.json](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23666.json)

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