The vulnerability CVE-2025-61765 affects the python-socketio package, 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, python-socketio uses a message queue backend such as Redis to facilitate inter-server communication. Messages exchanged between servers are serialized using Python's pickle module, which is inherently unsafe when deserializing untrusted data. The vulnerability arises because the server blindly deserializes messages received from the message queue using pickle.loads() without verifying their integrity or origin. If an attacker gains prior access to the message queue, they can inject malicious pickle payloads crafted to exploit Python's __reduce__ method, enabling arbitrary code execution within the context and privileges of the Socket.IO server process. This can lead to full compromise of the server hosting the python-socketio service. The vulnerability does not affect single-server deployments that do not use a message queue or multi-server setups with secure message queues that prevent unauthorized access. The root cause is the unsafe use of pickle for inter-server message serialization. The vendor mitigated this issue in version 5.14.0 by removing pickle serialization and switching to JSON encoding, which is much safer as it does not allow arbitrary code execution during deserialization. The CVSS v3.1 score of 6.4 reflects that the attack vector is adjacent network (message queue), requires low attack complexity but high privileges (prior message queue access), no user interaction, and impacts confidentiality, integrity, and availability. No known exploits are currently reported in the wild. Organizations using python-socketio in multi-server mode with Redis or similar message queues should upgrade promptly and ensure their message queue infrastructure is secured against unauthorized access to prevent exploitation.

For European organizations, this vulnerability poses a significant risk if they deploy python-socketio in multi-server configurations using message queues like Redis for inter-server communication. Successful exploitation allows attackers who have compromised the message queue to execute arbitrary code on Socket.IO servers, potentially leading to full server compromise, data theft, service disruption, or lateral movement within the network. This can impact confidentiality, integrity, and availability of critical real-time communication services. Industries relying on real-time data exchange such as finance, telecommunications, healthcare, and critical infrastructure in Europe could face operational disruptions and data breaches. The requirement for prior message queue access means that the initial compromise vector is likely through weak message queue security or network segmentation failures. Given the widespread use of Redis and python-socketio in cloud and on-premises deployments, the attack surface is non-trivial. Failure to patch or secure message queues could lead to targeted attacks against European organizations, especially those with complex multi-server Socket.IO deployments supporting real-time applications.

1. Upgrade all python-socketio deployments to version 5.14.0 or later, which replaces pickle serialization with JSON encoding, eliminating the unsafe deserialization vector. 2. Harden message queue infrastructure (e.g., Redis) by enforcing strong authentication, network segmentation, and access controls to prevent unauthorized access. 3. Monitor message queue access logs for suspicious activity indicative of compromise or unauthorized message injection. 4. Implement network-level controls such as firewall rules and VPNs to restrict access to message queues only to trusted servers. 5. Conduct regular security audits and penetration testing focused on message queue security and inter-server communication channels. 6. Consider deploying intrusion detection/prevention systems that can detect anomalous message queue traffic or unusual deserialization attempts. 7. For legacy systems where immediate upgrade is not feasible, isolate message queues in secure network zones and restrict access to minimize risk. 8. Educate development and operations teams about the dangers of unsafe deserialization and the importance of secure inter-process communication. 9. Review and update incident response plans to include scenarios involving message queue compromise and python-socketio exploitation. 10. Stay informed about any emerging exploits or patches related to this vulnerability.