CVE-2026-57099 Microsoft CVE debrief

Who should care

Defenders responsible for ASP.NET Core deployments should assess exposure and potential impact. They should prioritize verifying exposure, assessing potential impact on affected systems, and applying vendor-provided patches or mitigations. Additionally, defenders should monitor for potential denial-of-service attacks against ASP.NET Core deployments.

Why it matters

CVE-2026-57099 is a high-severity vulnerability in ASP.NET Core that allows an unauthorized attacker to deny service over a network. Defenders responsible for ASP.NET Core deployments should assess exposure and potential impact, and prioritize applying vendor-provided patches or mitigations.

• Potential denial-of-service attacks against ASP.NET Core deployments
• Need to verify exposure and assess potential impact on affected systems
• Priority to apply vendor-provided patches or mitigations

Technical summary

The vulnerability is caused by an allocation of resources without limits or throttling in ASP.NET Core, allowing 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. This vulnerability impacts ASP.NET Core deployments, potentially allowing attackers to cause denial-of-service attacks. Affected systems require verification of exposure and assessment of potential impact.

Defensive priority

Defenders should prioritize verifying exposure and assessing potential impact on ASP.NET Core deployments.

Recommended defensive actions

• Verify exposure of ASP.NET Core deployments to this vulnerability
• Assess potential impact on affected systems
• Apply vendor-provided patches or mitigations
• Monitor for potential denial-of-service attacks

Evidence notes

The vulnerability is described as an allocation of resources without limits or throttling in ASP.NET Core, allowing an unauthorized attacker to deny service over a network.

Sources and 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.