Horovod up to version 0.28.1 contains a CWE-502 insecure deserialization vulnerability in its KVStore HTTP server used for distributed task coordination. The server does not enforce authentication or authorization, permitting any remote attacker to send arbitrary data through HTTP PUT requests. When a Horovod worker retrieves data via HTTP GET, it deserializes it using cloudpickle.loads() without validation, enabling execution of attacker-controlled code. This vulnerability can result in remote code execution with full impact on confidentiality, integrity, and availability. No patch or official remediation has been documented as of the published date.

An attacker can remotely execute arbitrary code on a Horovod worker by exploiting the insecure deserialization of attacker-controlled data in the KVStore server. This compromises confidentiality, integrity, and availability of the affected system. The vulnerability is critical with a CVSS score of 9.8, indicating high potential impact if exploited. There are no known exploits in the wild at this time.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should consider restricting network access to the KVStore HTTP server to trusted entities only and avoid exposing it to untrusted networks. Monitoring for unusual HTTP PUT requests to the KVStore server may help detect exploitation attempts.