Horovod thru 0.28.1 contains an insecure deserialization vulnerability (CWE-502) in its KVStore HTTP server component. The KVStore server, used for distributed task coordination, lacks authentication and authorization controls, allowing any remote attacker to write arbitrary data via HTTP PUT requests. When a Horovod worker reads data from the KVStore (via HTTP GET), it deserializes the data using cloudpickle.loads() without verifying its source or integrity. An attacker can exploit this by sending a malicious pickle payload to the server before the legitimate data is written, causing the victim worker to deserialize and execute arbitrary code, leading to remote code execution.

Unauthenticated Remote Code Execution in ElasticRendezvousHandler in horovod/horovod

Horovod versions up to and including v0.28.1 are vulnerable to unauthenticated remote code execution. The vulnerability is due to improper handling of base64-encoded data in the `ElasticRendezvousHandler`, a subclass of `KVStoreHandler`. Specifically, the `_put_value` method in `ElasticRendezvousHandler` calls `codec.loads_base64(value)`, which eventually invokes `cloudpickle.loads(decoded)`. This allows an attacker to send a malicious pickle object via a PUT request, leading to arbitrary code execution on the server.

Insecure Temporary File in horovod/horovod

Insecure Temporary File in GitHub repository horovod/horovod prior to 0.24.0.