CVE-2026-31234
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedHorovod 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceHorovod's KVStore HTTP server lacks authentication, allowing unauthenticated HTTP PUT requests to write arbitrary data. When workers retrieve this data via HTTP GET and deserialize it using cloudpickle.loads() without validation, a remote attacker can supply a malicious pickle payload that executes arbitrary code on the victim worker.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Confirm Horovod installationRun `pip show horovod` or `python -c import horovod; print(horovod.__version__)` to verify Horovod is installedAffected if Horovod is not installed, the system is not affected by this CVE
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Identify KVStore HTTP server configurationReview Horovod configuration files and code for KVStore parameters such as `HOROVOD_KVSTORE`, `KVSTORE`, or similar environment variables that enable the HTTP-based KVStoreAffected if KVStore is configured to use HTTP transport (e.g., KVStore type is set to HTTP or a similar non-native backend) and is accessible over the network
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Verify network exposure of KVStore HTTP serviceCheck if the KVStore HTTP port (typically 5000-6000 range or as configured) is bound to an IP address accessible from untrusted networks, or if firewall rules allow external accessAffected if The KVStore HTTP server is listening on a publicly accessible IP or is not firewalled from untrusted network segments
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Inspect deserialization implementationSearch Horovod source code and runtime environment for uses of `cloudpickle.loads()` on data retrieved from the KVStore HTTP endpoint without prior validation or signature checkingAffected if The code uses cloudpickle.loads() directly on HTTP GET response data without sanitization or safe deserialization guards
A system is affected if it runs Horovod with an HTTP-based KVStore that is network-accessible and deserializes retrieved data with cloudpickle.loads() without validation.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataImplement authentication and authorization on the KVStore HTTP server, replace cloudpickle.loads() with safe deserialization, and/or network-isolate the KVStore to prevent unauthorized access.
- Consultation8.0 h
- Implementation24.0 h
- Testing12.0 h
- Review / QA8.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $14,656.
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Free · runs locallyCheck whether your project pulls in CVE-2026-31234 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-31234 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
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- Version or environment caveats, and links to real fixes
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