PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-47303 Microsoft CVE debrief

CVE-2026-47303 is an authentication bypass vulnerability in ASP.NET Core that allows an authorized attacker to elevate privileges over a network. The vulnerability has a CVSS score of 8.8 and is classified as HIGH severity. Microsoft .NET, Visual Studio 2022, and Visual Studio 2026 are affected. The vulnerability is caused by authentication bypass by assumed-immutable data in ASP.NET Core. An authorized attacker can exploit this vulnerability to elevate privileges over a network. The CVSS vector is CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Developers and administrators using ASP.NET Core, .NET, Visual Studio 2022, and Visual Studio 2026 should be aware of this vulnerability and take necessary actions to mitigate it.

Vendor
Microsoft
Product
.NET 10.0
CVSS
HIGH 8.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-14
Original CVE updated
2026-07-22
Advisory published
2026-07-14
Advisory updated
2026-07-22

Who should care

Developers and administrators using ASP.NET Core, .NET, Visual Studio 2022, and Visual Studio 2026 should be aware of this vulnerability and take necessary actions to mitigate it. They should review and update their installations, monitor for suspicious activity, and implement additional security measures.

Technical summary

The vulnerability is caused by authentication bypass by assumed-immutable data in ASP.NET Core. An authorized attacker can exploit this vulnerability to elevate privileges over a network. The CVSS vector is CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. This vulnerability affects Microsoft .NET, Visual Studio 2022, and Visual Studio 2026.

Defensive priority

High priority should be given to patching affected systems, especially those exposed to the internet. Additional security measures such as network segmentation and access controls should be implemented.

Recommended defensive actions

  • Apply patches provided by Microsoft
  • Review and update .NET, Visual Studio 2022, and Visual Studio 2026 installations
  • Monitor for suspicious activity
  • Implement additional security measures such as network segmentation and access controls
  • Review compensating controls for exposed systems while remediation is scheduled and verified

Evidence notes

The CVE record was published on 2026-07-14T19:17:08.707Z and was last modified on 2026-07-22T21:17:15.777Z. The NVD entry is currently Analyzed. This information is based on the NVD entry and CVE record. The vulnerability affects Microsoft .NET, Visual Studio 2022, and Visual Studio 2026. There is no evidence of exploitation in the wild, but an authorized attacker can exploit this vulnerability to elevate privileges over a network.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-47303 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-47303

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-47303 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-47303

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.