CVE-2025-3600 is a high-severity vulnerability identified in Progress Software's Telerik UI for ASP.NET AJAX, affecting versions from 2011.2.712 through 2025.1.218. The vulnerability stems from unsafe reflection, where externally-controlled input is used to select classes or code dynamically. This unsafe reflection can lead to an unhandled exception that causes the hosting process to crash, resulting in a denial of service (DoS) condition. Specifically, the vulnerability is categorized under CWE-400, which relates to uncontrolled resource consumption or exhaustion. The CVSS v3.1 base score is 7.5, indicating a high severity level. The vector details show that the attack can be executed remotely over the network (AV:N) with low attack complexity (AC:L), requires no privileges (PR:N), and no user interaction (UI:N). The scope is unchanged (S:U), and the impact affects availability only (A:H), with no confidentiality or integrity impact. Although no known exploits are reported in the wild yet, the vulnerability could be leveraged by attackers to disrupt services by crashing applications that use the vulnerable Telerik UI components. Since Telerik UI for ASP.NET AJAX is a widely used framework for building rich web applications, this vulnerability poses a significant risk to web services relying on it. The lack of available patches at the time of publication increases the urgency for mitigation through other means.

For European organizations, this vulnerability could lead to significant service disruptions, especially for those relying on Telerik UI for ASP.NET AJAX in their web applications. The denial of service caused by process crashes can result in downtime, affecting business continuity and potentially leading to financial losses and reputational damage. Critical sectors such as finance, healthcare, government, and e-commerce, which often use ASP.NET AJAX frameworks for interactive web portals, could be particularly impacted. Additionally, the vulnerability does not compromise data confidentiality or integrity but can degrade availability, which in regulated industries may lead to compliance issues. The ease of remote exploitation without authentication or user interaction increases the risk of automated attacks or scanning by malicious actors targeting exposed web applications. Organizations with public-facing web services using the affected Telerik versions are at higher risk, and the impact could cascade if the DoS affects backend systems or dependent services.

Given the absence of an official patch at the time of this report, European organizations should implement immediate compensating controls. First, conduct an inventory to identify all instances of Telerik UI for ASP.NET AJAX in use and verify their versions. Where possible, upgrade to a non-vulnerable version once available. Until then, restrict external access to vulnerable web applications using network-level controls such as Web Application Firewalls (WAFs) configured to detect and block suspicious requests that attempt to exploit unsafe reflection patterns. Implement rate limiting and anomaly detection to prevent automated exploitation attempts. Review and harden application input validation to ensure that inputs controlling reflection mechanisms are sanitized and constrained. Monitor application logs for unhandled exceptions or crashes indicative of exploitation attempts. Additionally, consider deploying application-level sandboxing or isolation to limit the impact of crashes on critical services. Engage with Progress Software for updates and patches, and plan for timely deployment once released.