CVE-2026-70188

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HTTP Request Smuggling in ASP.NET Core

Publication date: 2026-10-13

Last updated on: 2026-10-14

Assigner: Microsoft Corporation

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.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-10-13

Last Modified

2026-10-14

Generated

2026-10-19

AI Q&A

2026-10-14

EPSS Evaluated

2026-10-18

NVD

CVE-2026-70188

EUVD

EUVD-2026-99700

Affected Vendors & Products

Vendor	Product	Version / Range
Microsoft	ASP.NET	Core 10.0 10.0
Microsoft	ASP.NET	Core 11.0 11.0
Microsoft	ASP.NET	Core 8.0 8.0
Microsoft	ASP.NET	Core 9.0 9.0
Microsoft	Microsoft	Visual Studio 2022 version 17.14 17.14.0
Microsoft	Microsoft	Visual Studio 2026 version 18.10 18.10.0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-444	The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.

Attack-Flow Graph

Executive Summary

This vulnerability involves inconsistent interpretation of HTTP requests, known as HTTP request/response smuggling, in ASP.NET Core. An unauthorized attacker can exploit this to bypass a security feature over a network.

Impact Analysis

An attacker could bypass security features, potentially gaining unauthorized access to sensitive data or functionality. This could lead to data breaches or other security incidents.

Compliance Impact

This vulnerability allows unauthorized attackers to bypass security features via HTTP request smuggling, which could lead to unauthorized data access or manipulation. This may violate compliance requirements under GDPR (data protection) and HIPAA (health data security) by enabling unauthorized access to sensitive information.

Mitigation Strategies

Apply the latest security updates from Microsoft for ASP.NET Core versions 8.0, 9.0, 10.0, and 11.0 to address the inconsistent HTTP request interpretation issue.

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