CVE-2025-66524 is a deserialization vulnerability classified under CWE-502 affecting Apache NiFi versions 1.20.0 through 2.6.0. The issue resides in the GetAsanaObject Processor, which integrates with a configurable Distributed Map Cache Client Service to store and retrieve state information. This 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. Because Java deserialization is inherently unsafe when processing untrusted data, an attacker who can write crafted serialized objects into the cache server can trigger deserialization of malicious payloads when NiFi reads from the cache. This can lead to remote code execution or other severe impacts on confidentiality, integrity, and availability. Exploitation requires that the attacker have direct access to the cache server configured for the GetAsanaObject Processor and that the NiFi instance is running this processor. The vulnerability does not require user interaction but does require privileged access to the cache server and NiFi environment. The recommended mitigation is upgrading to Apache NiFi 2.7.0, which replaces Java serialization with safer JSON serialization, eliminating the unsafe deserialization vector. Alternatively, removing the GetAsanaObject Processor from the NiFi deployment also prevents exploitation. No public exploits are known at this time, but the vulnerability is rated high severity with a CVSS 4.0 score of 7.5, reflecting the significant impact potential balanced by the complexity and access requirements.

For European organizations, the impact of CVE-2025-66524 can be substantial, particularly for those relying on Apache NiFi for data flow automation and integration. Successful exploitation could allow attackers to execute arbitrary code within the NiFi environment, potentially leading to data breaches, disruption of data pipelines, and compromise of downstream systems. This is especially critical for sectors such as finance, healthcare, energy, and government, where NiFi may be used to process sensitive or regulated data. The requirement for direct access to the cache server somewhat limits the attack surface but does not eliminate risk, as internal threat actors or attackers who have breached perimeter defenses could leverage this vulnerability. The integrity and availability of data flows could be severely impacted, causing operational downtime and loss of trust. Given NiFi’s role in orchestrating data flows, exploitation could also facilitate lateral movement within networks. Organizations with complex distributed cache configurations are at higher risk. The absence of known exploits provides a window for proactive mitigation before active attacks emerge.

1. Upgrade Apache NiFi to version 2.7.0 or later, which replaces unsafe Java object serialization with JSON serialization in the GetAsanaObject Processor, 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 and monitor access to the Distributed Map Cache Client Service and cache servers, ensuring only authorized systems and users can interact with them. 4. Implement network segmentation and firewall rules to isolate cache servers from untrusted networks and limit exposure. 5. Conduct regular audits of NiFi processors and configurations to detect unauthorized changes or presence of vulnerable processors. 6. Employ runtime application self-protection (RASP) or endpoint detection and response (EDR) solutions to detect anomalous behavior indicative of deserialization attacks. 7. Maintain up-to-date backups and incident response plans tailored to NiFi environments to minimize impact if exploitation occurs. 8. Monitor security advisories and threat intelligence feeds for any emerging exploits targeting this vulnerability.