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CVE-2026-56170 Microsoft CVE debrief

A high-severity vulnerability CVE-2026-56170 was found in ASP.NET Core, which allows an unauthorized attacker to deny service over a network. The vulnerability has a CVSS score of 7.5 and is classified as HIGH. Microsoft .NET versions 8.0.0 to 8.0.29, 9.0.0 to 9.0.18, and 10.0.0 to 10.0.6 are affected. The vulnerability is caused by allocation of resources without limits or throttling in ASP.NET Core. This allows an unauthorized attacker to deny service over a network. Users of affected .NET versions should apply patches to prevent denial of service attacks.

Vendor
Microsoft
Product
.NET 10.0
CVSS
HIGH 7.5
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

Users of Microsoft .NET versions 8.0.0 to 8.0.29, 9.0.0 to 9.0.18, and 10.0.0 to 10.0.6 should apply patches to prevent denial of service attacks. Affected operators include .NET developers and administrators. Platform impact includes denial of service attacks. Vulnerability-management impact includes applying patches and verifying affected scope. Security-team impact includes monitoring for suspicious network activity.

Technical summary

The vulnerability is caused by allocation of resources without limits or throttling in ASP.NET Core. This allows an unauthorized attacker to deny service over a network. The CVSS vector is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Affected product context includes Microsoft .NET versions 8.0.0 to 8.0.29, 9.0.0 to 9.0.18, and 10.0.0 to 10.0.6. Defensive impact includes denial of service attacks.

Defensive priority

High priority should be given to patching affected .NET versions to prevent denial of service attacks.

Recommended defensive actions

  • Apply patches for affected .NET versions
  • Inventory and verify .NET versions
  • Monitor for suspicious network activity
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record was published on 2026-07-14T17:17:10.140Z and was last modified on 2026-07-22T21:17:56.337Z. The NVD entry is currently Analyzed. The vulnerability affects Microsoft .NET versions 8.0.0 to 8.0.29, 9.0.0 to 9.0.18, and 10.0.0 to 10.0.6. The CVSS vector is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Evidence limits suggest that further verification is required to confirm affected scope and severity.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-56170 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-56170

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

  • CVE-2026-56170 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-56170

    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.