CVE-2025-24011: 
C# vulnerability analysis and mitigation

Umbraco, a free and open source .NET content management system, contains a vulnerability (CVE-2025-24011) that allows attackers to determine whether an account exists by analyzing response codes and timing of Umbraco management API responses. This vulnerability affects versions starting from 14.0.0 and prior to versions 14.3.2 and 15.1.2. The issue was disclosed on January 21, 2025 (GitHub Advisory).

The vulnerability is related to the timing and response behavior of the Umbraco management API. The system's login endpoint reveals information about account existence through observable timing differences in responses. The vulnerability has been assigned a CVSS v3.1 score of 5.3 (Medium), with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N, indicating it is network-accessible, requires low attack complexity, and needs no privileges or user interaction (GitHub Advisory).

The vulnerability allows attackers to enumerate valid user accounts in the system by analyzing the timing and response codes of the management API. This information disclosure could be used as a stepping stone for further attacks such as brute force attempts or targeted phishing campaigns (GitHub Advisory).

The vulnerability has been patched in versions 14.3.2 and 15.1.2. The fix implements a TimedScope mechanism to ensure consistent response times for both valid and invalid login attempts. No workarounds are available for unpatched versions (GitHub Advisory).