CVE-2026-70188: ASP.NET Core Security Feature Bypass Vulnerability

Overview

Severity
Critical (CVSS 9.1)
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C
Category
Security Feature Bypass
Exploit Status
Not Exploited
Exploitation Likelihood
Less Likely
Patch Tuesday
2026-Oct
Released
2026-10-13

Description

Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an unauthorized attacker to bypass a security feature over a network.

FAQ

What kind of security feature could be bypassed by successfully exploiting this vulnerability? The authentication feature could be bypassed as this vulnerability allows impersonation. How could an attacker exploit this vulnerability? An unauthenticated attacker could exploit this vulnerability by sending specially crafted HTTP/2 requests to an affected server. Successful exploitation could allow the attacker to bypass access controls and reach protected resources. No authentication or user interaction is required.

Affected Products (6)

Developer Tools

  • Microsoft Visual Studio 2026 version 18.10
  • Microsoft Visual Studio 2022 version 17.14
  • ASP.NET Core 11.0
  • ASP.NET Core 9.0
  • ASP.NET Core 10.0
  • ASP.NET Core 8.0

Security Updates (4)

Acknowledgments

<a href="https://www.linkedin.com/in/hyperxpro/">Aayush Atharva</a>

Revision History

  • 2026-10-13: Information published.