CVE-2025-55247: 
C# vulnerability analysis and mitigation

CVE-2025-55247 is a vulnerability in .NET that involves improper link resolution before file access ('link following'). The vulnerability was discovered and disclosed on October 14, 2025, affecting .NET Core systems. This security flaw specifically impacts MSBuild's temporary directories on Linux systems, where predictable paths can be exploited (Ubuntu Security, NVD).

The vulnerability has been assigned a CVSS v3.1 Base Score of 7.3 (HIGH) with the following vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H. The vulnerability is classified under CWE-59 (Improper Link Resolution Before File Access). The technical nature of the flaw involves predictable paths for MSBuild's temporary directories on Linux systems, which can be exploited when another user creates the directories ahead of MSBuild (NVD).

The vulnerability allows an authorized attacker to elevate privileges locally. Additionally, it can lead to a Denial of Service (DoS) condition affecting builds when an attacker creates directories ahead of MSBuild (Ubuntu Security).

Multiple versions of .NET are affected, including .NET 8, 9, and 10. Ubuntu has marked several distributions as vulnerable, including versions 25.10, 25.04, and 24.04 LTS. Users are advised to update their systems once patches are available (Ubuntu Security).