CVE-2025-66524 is a deserialization vulnerability classified under CWE-502 found in Apache NiFi versions 1.20.0 through 2.6.0, specifically in the GetAsanaObject Processor component. This processor integrates with a configurable Distribute Map Cache Client Service to store and retrieve state information. The vulnerability arises because the processor uses Java's native object serialization and deserialization mechanisms without applying any filtering or validation on the serialized data retrieved from the cache server. This lack of filtering allows an attacker with direct access to the cache server to inject crafted serialized objects that, when deserialized by NiFi, could lead to arbitrary code execution, data manipulation, or denial of service. Exploitation requires that the attacker has network access to the cache server configured for the GetAsanaObject Processor and that the NiFi instance is running with this processor enabled. The vulnerability does not require user interaction but does require privileges to access the cache server and NiFi environment. The recommended mitigation is upgrading to Apache NiFi version 2.7.0, which replaces Java object serialization with safer JSON serialization, effectively eliminating the deserialization risk. Alternatively, removing the GetAsanaObject Processor from the NiFi deployment also prevents exploitation. No known exploits are currently reported in the wild, but the vulnerability's nature and high CVSS score indicate a significant risk if exploited. The vulnerability impacts confidentiality, integrity, and availability of the NiFi system and potentially connected systems due to NiFi's role in data flow management.

For European organizations, this vulnerability poses a significant risk, especially for those relying on Apache NiFi for critical data flow and integration tasks. Successful exploitation could lead to unauthorized code execution within the NiFi environment, potentially compromising sensitive data, disrupting automated workflows, and causing service outages. This could impact sectors such as finance, healthcare, manufacturing, and government services that use NiFi for real-time data processing and integration. The requirement for direct access to the cache server limits the attack surface but does not eliminate risk, particularly in environments where internal network segmentation is weak or where cache servers are exposed to less trusted networks. The compromise of NiFi could also serve as a pivot point for lateral movement within an organization's network, amplifying the impact. Given NiFi's use in data pipelines, data integrity and availability disruptions could have cascading effects on dependent systems and business processes.

1. Upgrade Apache NiFi to version 2.7.0 or later, which replaces Java object serialization with JSON serialization, effectively mitigating the vulnerability. 2. If immediate upgrade is not feasible, remove or disable the GetAsanaObject Processor from the NiFi deployment to eliminate the vulnerable component. 3. Restrict network access to the Distribute Map Cache Client Service cache servers, ensuring they are not accessible from untrusted networks or users. 4. Implement strict network segmentation and firewall rules to limit access to NiFi cache servers only to authorized systems and personnel. 5. Monitor NiFi and cache server logs for unusual deserialization activity or unexpected cache entries that could indicate exploitation attempts. 6. Conduct regular security audits and vulnerability assessments focusing on NiFi deployments and their integration points. 7. Educate administrators about the risks of deserialization vulnerabilities and the importance of applying security patches promptly. 8. Consider deploying runtime application self-protection (RASP) or endpoint detection and response (EDR) solutions to detect anomalous behavior indicative of exploitation attempts.