CVE-2025-59465 is a vulnerability in the Node.js runtime affecting its HTTP/2 implementation. Specifically, when the Node.js server receives a malformed HTTP/2 HEADERS frame containing oversized or invalid HPACK-encoded data, it triggers an unhandled error on the TLSSocket layer, resulting in an ECONNRESET error. Instead of gracefully handling this error and closing the connection, the Node.js process crashes, causing a denial of service. This vulnerability arises because many Node.js applications do not attach explicit error handlers to secure sockets, allowing the unhandled error to propagate and terminate the process. The affected versions span from early major releases (4.0) up to recent ones (25.2.1), indicating a long-standing issue across multiple Node.js versions. The vulnerability is classified under CWE-400 (Uncontrolled Resource Consumption), as the malformed frame causes resource exhaustion leading to a crash. The CVSS v3.0 score is 7.5 (high), reflecting network attack vector, no privileges or user interaction required, and a high impact on availability. No patches are linked yet, and no known exploits have been reported in the wild. The vulnerability primarily impacts applications serving HTTP/2 over TLS, which is common in modern web services built on Node.js.

For European organizations, the impact of CVE-2025-59465 can be significant, especially for those relying on Node.js for critical web services or APIs using HTTP/2 over TLS. A successful exploit can cause service outages by crashing Node.js processes, leading to denial of service conditions that disrupt business operations, customer access, and potentially damage reputation. Industries such as finance, e-commerce, healthcare, and government services that depend on high availability and secure web communications are particularly at risk. The vulnerability does not expose data confidentiality or integrity directly but affects availability, which can indirectly impact trust and compliance with regulations like GDPR if service disruptions affect data access or processing. The ease of remote exploitation without authentication increases the threat level, as attackers can trigger crashes without insider access. Organizations with insufficient error handling or lacking robust process management (e.g., automatic restarts) may experience prolonged downtime.

To mitigate CVE-2025-59465, European organizations should: 1) Upgrade Node.js to a version where this vulnerability is patched once available; 2) In the interim, implement explicit error handlers on all secure sockets by attaching 'error' event listeners to TLSSocket instances to prevent unhandled exceptions from crashing the process; 3) Employ robust process management tools (e.g., PM2, systemd) to automatically restart Node.js processes upon crashes to minimize downtime; 4) Monitor HTTP/2 traffic for malformed HEADERS frames or abnormal HPACK data patterns that could indicate exploitation attempts; 5) Apply network-level protections such as rate limiting and Web Application Firewalls (WAFs) configured to detect and block suspicious HTTP/2 frames; 6) Conduct thorough testing of Node.js applications to ensure error handling is comprehensive and resilient; 7) Review and update incident response plans to include scenarios involving DoS via malformed HTTP/2 frames. These steps go beyond generic advice by focusing on specific error handling and operational resilience tailored to this vulnerability.