CVE-2025-55315: 
C# vulnerability analysis and mitigation

ASP.NET Core contains a security vulnerability (CVE-2025-55315) involving inconsistent interpretation of HTTP requests, specifically related to HTTP request/response smuggling. This vulnerability allows an authorized attacker to bypass security features over a network. The vulnerability was disclosed on October 14, 2025, and affects ASP.NET Core implementations (NVD, Ubuntu).

The vulnerability has been assigned a CVSS v3.1 base score of 9.9 (Critical) with the following vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L. The vulnerability is classified under CWE-444 (Inconsistent Interpretation of HTTP Requests). The attack vector is network-based, requires low attack complexity, needs low privileges, and no user interaction (NVD).

The vulnerability has significant impact potential, affecting confidentiality and integrity at a high level, while having a low impact on availability. The critical CVSS score of 9.9 indicates that successful exploitation could lead to serious security consequences (NVD).

Multiple Linux distributions have begun evaluating and addressing the vulnerability. Ubuntu has marked the vulnerability as 'Needs evaluation' for version 22.04 LTS (jammy), while newer versions are marked as 'Vulnerable' and await patches. Organizations running ASP.NET Core should monitor vendor announcements for security updates (Ubuntu).

The vulnerability has been included in Microsoft's October 2025 Patch Tuesday release, which addressed a total of 172 security flaws. The security community has classified this as an 'Important' severity issue requiring prompt attention (Bleeping Computer).