CVE-2025-61765: miguelgrinberg python-socketio Deserialization of Untrusted Data

Vulnerability summary

CVE-2025-61765 is a medium (CVSS 6.4) Deserialization of Untrusted Data vulnerability in miguelgrinberg python-socketio. EPSS estimates a 0.48% chance of exploitation in the next 30 days, higher than 40.1% of scored vulnerabilities.

Timeline

1. 06-10-2025
   PublishedVulnerability first disclosed.
2. 22-10-2025
   Last modifiedVulnerability information updated.

Description

python-socketio is a Python implementation of the Socket.IO realtime client and server. A remote code execution vulnerability in python-socketio versions prior to 5.14.0 allows attackers to execute arbitrary Python code through malicious pickle deserialization in multi-server deployments on which the attacker previously gained access to the message queue that the servers use for internal communications. When Socket.IO servers are configured to use a message queue backend such as Redis for inter-server communication, messages sent between the servers are encoded using the `pickle` Python module. When a server receives one of these messages through the message queue, it assumes it is trusted and immediately deserializes it. The vulnerability stems from deserialization of messages using Python's `pickle.loads()` function. Having previously obtained access to the message queue, the attacker can send a python-socketio server a crafted pickle payload that executes arbitrary code during deserialization via Python's `__reduce__` method. This vulnerability only affects deployments with a compromised message queue. The attack can lead to the attacker executing random code in the context of, and with the privileges of a Socket.IO server process. Single-server systems that do not use a message queue, and multi-server systems with a secure message queue are not vulnerable. In addition to making sure standard security practices are followed in the deployment of the message queue, users of the python-socketio package can upgrade to version 5.14.0 or newer, which remove the `pickle` module and use the much safer JSON encoding for inter-server messaging.

• CWE-502Deserialization of Untrusted DataThe product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.