CVE-2025-55184 is a vulnerability in Meta's React Server Components, specifically affecting versions 19.0.0 through 19.2.1 and associated packages like react-server-dom-parcel, react-server-dom-turbopack, and react-server-dom-webpack. The root cause is unsafe deserialization of untrusted data received via HTTP requests targeting Server Function endpoints. This deserialization flaw can lead to an infinite loop within the server process, resulting in uncontrolled resource consumption and effectively causing a denial of service (DoS) condition. The vulnerability does not require any authentication or user interaction, making it remotely exploitable by unauthenticated attackers. The CVSS v3.1 score of 7.5 reflects a high severity, primarily due to the impact on availability (denial of service) and the ease of exploitation (network vector, no privileges required). While no public exploits have been reported yet, the vulnerability's nature suggests that attackers could disrupt web services relying on these React Server Components by sending crafted payloads that trigger the infinite loop. The affected packages are widely used in modern web application development to enable server-side rendering and interactivity, which increases the potential attack surface. The lack of available patches at the time of publication necessitates immediate mitigation strategies to protect affected systems.

For European organizations, this vulnerability poses a significant risk to the availability of web applications and services built using the affected React Server Components. A successful exploitation can cause server processes to hang indefinitely, leading to denial of service conditions that disrupt business operations, degrade user experience, and potentially cause financial losses. Organizations providing critical online services, e-commerce platforms, or public-facing portals using these components may face service outages. Additionally, the pre-authentication nature of the vulnerability means that attackers can exploit it without any credentials, increasing the likelihood of automated attacks or denial of service campaigns. The impact is particularly severe for high-traffic environments where resource exhaustion can cascade, affecting multiple services or leading to broader infrastructure instability. Given the widespread adoption of React frameworks in Europe’s digital economy, the vulnerability could affect a broad range of sectors including finance, government, healthcare, and technology. The inability to serve legitimate HTTP requests during an attack could also harm organizational reputation and customer trust.

1. Immediate mitigation should focus on implementing strict input validation and sanitization for all data received by Server Function endpoints to prevent malicious payloads from triggering unsafe deserialization. 2. Deploy rate limiting and request throttling on endpoints handling Server Function calls to reduce the risk of resource exhaustion from repeated exploit attempts. 3. Isolate the server processes handling React Server Components in separate containers or sandboxes to limit the impact of a potential hang or crash. 4. Monitor server performance and set up alerts for unusual CPU or memory usage patterns indicative of infinite loops or resource consumption spikes. 5. Until official patches are released by Meta, consider temporarily disabling or restricting access to vulnerable Server Function endpoints if feasible. 6. Keep abreast of updates from Meta and apply security patches promptly once available. 7. Conduct thorough code reviews and security testing focusing on deserialization logic and server-side request handling. 8. Employ Web Application Firewalls (WAFs) with custom rules to detect and block suspicious payloads targeting deserialization endpoints. 9. Educate development teams about secure coding practices related to deserialization and resource management in server-side components.