CVE-2020-36518 is a denial of service vulnerability affecting versions of the jackson-databind library prior to 2.13.0. Jackson-databind is a widely used Java library for serializing and deserializing JSON data. The vulnerability arises when the library processes JSON input containing an excessively deep level of nested objects. This causes the Java runtime to throw a StackOverflowError due to the recursive nature of the deserialization process. Specifically, the recursive calls to parse nested JSON objects exhaust the call stack, leading to an unhandled exception that crashes the application or service using the library. This results in a denial of service (DoS) condition, as the affected application becomes unavailable or unstable. There is no indication that this vulnerability allows for remote code execution or data leakage; its impact is limited to availability. The vulnerability does not require authentication or user interaction beyond submitting crafted JSON input to the affected service. No known exploits have been reported in the wild, and no official patches or vendor advisories are linked in the provided information. However, the fix is known to be included starting from jackson-databind version 2.13.0, which presumably implements input validation or limits on nesting depth to prevent stack overflow. Given the widespread use of jackson-databind in Java applications, especially in web services and APIs that consume JSON, this vulnerability could be triggered remotely by an attacker sending maliciously crafted JSON payloads to vulnerable endpoints. The absence of a CVSS score suggests the vulnerability has not been formally scored, but the technical details and impact are clear enough to assess severity.

For European organizations, the primary impact of CVE-2020-36518 is service disruption due to denial of service. Organizations relying on Java applications that use jackson-databind versions before 2.13.0 for JSON processing—such as web servers, microservices, API gateways, and backend systems—may experience outages or degraded service if targeted with deeply nested JSON payloads. This can affect availability of critical business applications, customer-facing services, and internal tools. Industries with high reliance on Java-based middleware, including finance, telecommunications, government, and e-commerce sectors, could face operational interruptions. While no data confidentiality or integrity compromise is indicated, the loss of availability can lead to financial losses, reputational damage, and regulatory compliance issues, especially under EU regulations like GDPR if service interruptions affect data processing timelines. The vulnerability's ease of exploitation (no authentication or user interaction required) increases the risk of automated or opportunistic attacks. However, the lack of known exploits in the wild and the availability of a fixed version reduce immediate risk if organizations maintain up-to-date dependencies. Legacy systems or those with slow patch cycles are most vulnerable. Overall, the threat is significant for availability but does not pose direct risks to data breach or system takeover.

European organizations should take the following specific mitigation steps: 1) Inventory all Java applications and services to identify usage of jackson-databind and determine the version in use. 2) Upgrade jackson-databind to version 2.13.0 or later, where the vulnerability is fixed. 3) If immediate upgrade is not feasible, implement input validation at the application or API gateway level to detect and block JSON payloads with excessive nesting depth. This can be done by configuring JSON parsers or using web application firewalls (WAFs) with custom rules to limit recursion depth or payload complexity. 4) Monitor application logs for StackOverflowError or related exceptions indicating attempted exploitation. 5) Employ rate limiting and anomaly detection on endpoints that accept JSON input to reduce the risk of DoS attacks. 6) Conduct security testing and code reviews to ensure no other deserialization vulnerabilities exist. 7) Educate developers and DevOps teams about the risks of deserialization and the importance of dependency management. 8) Maintain an up-to-date software bill of materials (SBOM) to quickly identify vulnerable components in the future. These measures go beyond generic advice by focusing on practical detection, prevention, and remediation tailored to this specific vulnerability and its exploitation vector.