CVE-2026-31234 Horovod contains an insecure deserialization vulnerability in its KVStore HTTP server component
Remote attackers can achieve arbitrary code execution by injecting malicious pickle payloads into the unauthenticated KVStore HTTP server.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-31234?
CVE-2026-31234 is a critical unsafe deserialization vulnerability in n/a, published on 12 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-502
Which versions are affected by CVE-2026-31234?
3 open source packages ship an affected version, including horovod.
| Package | Affected | Fixed in |
|---|---|---|
horovod PyPI | All versions to 0.28.1 | None |
horovod PyPI | All versions to 0.28.1 | None |
horovod PyPI | All versions to 0.28.1 | None |
How do I fix CVE-2026-31234?
No fix has been published for CVE-2026-31234 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-31234 being exploited?
There is no known exploitation of CVE-2026-31234 in the wild and no public exploit code.
Sources
Also known as GHSA-mf8f-x4r3-jm8c, PYSEC-2026-354.