The vulnerability CVE-2025-61765 affects the python-socketio library, a Python implementation of the Socket.IO realtime client and server, specifically versions from 0.8.0 up to but not including 5.14.0. In multi-server deployments where python-socketio servers communicate via a message queue backend such as Redis, messages are serialized using Python's pickle module. The vulnerability arises because the receiving server blindly deserializes these messages using pickle.loads() without verifying their trustworthiness. If an attacker has previously compromised the message queue, they can inject malicious pickle payloads that exploit Python's __reduce__ method to execute arbitrary code on the server running python-socketio. This leads to remote code execution with the privileges of the Socket.IO server process. Single-server deployments or multi-server setups with secure message queues are not vulnerable. The root cause is the unsafe use of pickle for inter-server communication, which was replaced in version 5.14.0 by safer JSON encoding. The vulnerability requires the attacker to have prior access to the message queue, which is a high privilege requirement, but the impact on confidentiality and integrity is high, as arbitrary code execution is possible. The CVSS 3.1 base score is 6.4, reflecting these factors. No known exploits are currently reported in the wild. Mitigation involves upgrading to python-socketio 5.14.0 or newer and ensuring strict security controls around message queue access to prevent unauthorized message injection.

For European organizations, this vulnerability poses a significant risk primarily to those deploying python-socketio in multi-server configurations using message queues like Redis for inter-server communication. Successful exploitation allows attackers to execute arbitrary code within the context of the Socket.IO server process, potentially leading to data breaches, service disruption, or lateral movement within the network. Confidentiality and integrity of data handled by the affected servers are at high risk. Availability impact is lower but still possible if attackers disrupt services. Organizations relying on real-time communication platforms, collaborative applications, or IoT systems using python-socketio could face operational and reputational damage. The requirement for prior message queue access means that the vulnerability is often a secondary consequence of a prior compromise, emphasizing the need for layered security. Given the widespread use of Redis and similar message queues in European enterprises, especially in technology, finance, and telecommunications sectors, the threat is material. However, single-server deployments or those with properly secured message queues are not affected, limiting the scope somewhat.

1. Upgrade all python-socketio deployments to version 5.14.0 or later, which replaces pickle serialization with safer JSON encoding for inter-server messages. 2. Harden message queue security by implementing strong authentication, network segmentation, and encryption to prevent unauthorized access. 3. Monitor message queue access logs for unusual activity indicative of compromise. 4. Employ network-level controls such as firewall rules and VPNs to restrict message queue access to trusted servers only. 5. Conduct regular security audits and penetration tests focusing on message queue infrastructure. 6. For legacy systems that cannot upgrade immediately, consider isolating message queues and applying strict access controls to minimize exposure. 7. Educate development and operations teams about the risks of unsafe deserialization and secure coding practices. 8. Implement runtime application self-protection (RASP) or endpoint detection to detect anomalous behavior indicative of exploitation attempts. 9. Maintain up-to-date backups and incident response plans to quickly recover from potential compromises.