Vulnerability · Published May 12, 2026 · Assigned by mitre
CVE-2026-31234
Critical 9.8
In plain English
A critical-severity unsafe deserialization in the horovod package (PyPI). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 53% of all known vulnerabilities).
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | horovod | no fix listed | GHSA-mf8f-x4r3-jm8c |
| PyPI | horovod | no fix listed | PYSEC-2026-354 |
Affected products (as reported)
Weakness: CWE-502 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H