CVE-2025-26682 is a high-severity vulnerability identified in Microsoft ASP.NET Core 8.0, classified under CWE-770: Allocation of Resources Without Limits or Throttling. This vulnerability arises because the affected version of ASP.NET Core does not impose adequate limits or throttling on resource allocation during request processing. An unauthorized attacker can exploit this flaw remotely over the network without any authentication or user interaction. By sending a crafted sequence of requests or payloads, the attacker can cause the ASP.NET Core application to consume excessive system resources such as memory, CPU, or threads. This uncontrolled resource consumption can lead to denial of service (DoS), rendering the web application or service unavailable to legitimate users. The CVSS v3.1 base score of 7.5 reflects the high impact on availability, with no impact on confidentiality or integrity. The attack vector is network-based with low complexity and no privileges or user interaction required, making exploitation feasible in many environments. Currently, there are no known exploits in the wild, and no official patches have been linked yet, indicating that mitigation may rely on configuration changes or temporary workarounds until a vendor patch is released. This vulnerability is particularly critical for internet-facing ASP.NET Core 8.0 applications that handle high volumes of requests or operate in multi-tenant environments where resource exhaustion can have cascading effects.

For European organizations, the impact of CVE-2025-26682 can be significant, especially for those relying on ASP.NET Core 8.0 for critical web applications, APIs, or cloud services. A successful exploitation can cause service outages, disrupting business operations, customer access, and potentially leading to financial losses and reputational damage. Sectors such as finance, healthcare, government, and e-commerce, which often deploy ASP.NET Core applications, may face increased risk due to the critical nature of their services. Additionally, denial of service attacks can be leveraged as a smokescreen for other malicious activities or to cause operational chaos. Given the high availability requirements and regulatory frameworks in Europe (e.g., GDPR, NIS Directive), prolonged service disruptions could also result in compliance issues and penalties. The vulnerability's ease of exploitation without authentication increases the attack surface, making it a viable vector for opportunistic attackers or automated botnets targeting vulnerable endpoints.

1. Immediate mitigation should include implementing rate limiting and request throttling at the network edge or application gateway level to prevent excessive resource consumption from individual clients. 2. Employ Web Application Firewalls (WAFs) with custom rules to detect and block anomalous traffic patterns indicative of resource exhaustion attempts. 3. Monitor application and system resource utilization closely to identify early signs of exploitation or abnormal load spikes. 4. Where possible, configure ASP.NET Core applications to limit maximum concurrent requests and implement cancellation tokens to abort long-running requests. 5. Segment and isolate critical services to minimize the blast radius of potential DoS attacks. 6. Stay updated with Microsoft security advisories and apply patches promptly once available. 7. Conduct regular security assessments and penetration testing focusing on resource exhaustion scenarios. 8. Educate development and operations teams about secure coding and deployment practices related to resource management in ASP.NET Core.