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The CVE-2025-55315 vulnerability is an HTTP request/response smuggling flaw within the ASP.NET Core Kestrel web server. It stems from inconsistent parsing of malformed HTTP requests between Kestrel and potential downstream proxies or the application logic itself. A specially crafted HTTP request, containing discrepancies in headers like `Content-Length` and Transfer-Encoding, can be interpreted differently by various system components. This allows an authenticated attacker to “smuggle” a concealed HTTP request past security filters or gates. The smuggled request is then processed by the application as a separate, legitimate request, leading to a bypass of security features such as authentication or authorization mechanisms, effectively granting the attacker unauthorized access.
Platform: ASP.NET Core
Version: 10.0/9.0/8.0/2.3
Vulnerability: Feature Bypass
Severity: Critical
date: 2025-10-14
Prediction: 2025-10-21
What Undercode Say:
`dotnet –info`
`dotnet add package Microsoft.AspNetCore.Server.Kestrel.Core`
`Update-Package -Id Microsoft.AspNetCore.Server.Kestrel.Core`
How Exploit:
Crafted HTTP requests
Header inconsistency smuggling
Bypass authorization checks
Protection from this CVE:
Update .NET runtime
Patch Kestrel package
Recompile applications
Impact:
Security feature bypass
Unauthorized access
Privilege escalation
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Sources:
Reported By: github.com
Extra Source Hub:
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