CVE-2026-23864 identifies multiple denial of service (DoS) vulnerabilities in Meta's React Server Components ecosystem, specifically impacting the packages react-server-dom-parcel, react-server-dom-turbopack, and react-server-dom-webpack versions 19.0.0 through 19.2.0. The root causes are deserialization of untrusted data (CWE-502) and uncontrolled resource consumption (CWE-400). These vulnerabilities are exploitable by sending specially crafted HTTP requests to Server Function endpoints, which are part of React Server Components' architecture allowing server-side execution of component logic. When these malicious requests are processed, they can trigger server crashes, out-of-memory exceptions, or excessive CPU consumption depending on the code path exercised and the specific application configuration. This results in denial of service conditions, severely impacting application availability. The vulnerabilities do not require authentication or user interaction, increasing their risk profile. Although no known exploits have been reported in the wild, the potential impact on server stability is significant. The lack of a CVSS score necessitates a severity assessment based on impact and exploitability. The recommended mitigation is to upgrade to the latest package versions where these issues are addressed. Additionally, developers should audit server function endpoints to limit exposure, implement strict input validation, and monitor resource usage to detect anomalous activity. These vulnerabilities highlight the risks of deserializing untrusted data and the importance of resource management in server-side JavaScript frameworks.

For European organizations, the primary impact is on the availability of web applications using affected React Server Components versions. Denial of service conditions can lead to server crashes or resource exhaustion, causing downtime and degraded user experience. This can affect e-commerce platforms, SaaS providers, and internal business applications relying on React Server Components for server-side rendering or server function execution. The disruption may result in financial losses, reputational damage, and operational challenges. Organizations with high traffic volumes or critical web services are especially vulnerable, as resource exhaustion can cascade and affect other services. Additionally, the exploitation does not require authentication, increasing the attack surface and risk of automated attacks. The vulnerabilities may also complicate incident response and recovery due to unpredictable server behavior under attack. European data protection regulations emphasize service availability, so prolonged outages could also have compliance implications. Overall, the threat poses a significant risk to service continuity and operational resilience in European digital environments.

1. Upgrade all affected React Server Components packages (react-server-dom-parcel, react-server-dom-turbopack, react-server-dom-webpack) to the latest versions where these vulnerabilities are fixed. 2. Audit and restrict access to Server Function endpoints to minimize exposure to untrusted inputs, using network controls or authentication where feasible. 3. Implement strict input validation and sanitization on all data deserialized by server functions to prevent malicious payloads. 4. Monitor server resource usage (CPU, memory) closely to detect abnormal spikes indicative of exploitation attempts. 5. Employ rate limiting and anomaly detection on HTTP requests targeting server function endpoints to mitigate automated or volumetric attacks. 6. Conduct regular security reviews and penetration testing focused on server-side components and deserialization logic. 7. Educate development teams about secure deserialization practices and resource management in React Server Components. 8. Prepare incident response plans to quickly isolate and recover from denial of service events related to these vulnerabilities.