CVE-2026-18948 is a critical-severity (CVSS 9.9) Deserialization of Untrusted Data vulnerability in feast. A fix is available for feast — see the affected versions and patch details below.
Feast vulnerable to arbitrary code execution via unsafe deserialization of dill-serialized UDFs
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-18948.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
feastReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
A flaw was found in Feast. The system improperly deserializes user-defined functions (UDFs) stored in its registry, which are serialized using the 'dill' library. This allows a remote attacker to store a malicious UDF, leading to unauthenticated arbitrary code execution on the feature server in default configurations. An authenticated attacker can also achieve arbitrary code execution on the registry server by bypassing authorization checks during deserialization. This vulnerability can result in cross-tenant data access and lateral movement within the system.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | feast | all versions | 0.67.0pip install --upgrade 'feast==0.67.0' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for feast, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update feast to 0.67.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-18948 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This Critical vulnerability in Feast, as deployed within Red Hat OpenShift AI, allows for remote code execution due to unsafe deserialization of user-defined functions. An unauthenticated attacker can achieve RCE on the feature-server pod in default configurations, leading to cross-tenant data access and potential…
Configure Feast to enforce `auth.type: kubernetes` in the operator-generated configuration and deny registry writes by default. This measure limits the attack surface by requiring proper authentication and authorization for registry modifications, preventing the deserialization of malicious user-defined functions.Source: Red Hat security advisory for CVE-2026-18948 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat OpenShift AI 2.25 | rhoai/odh-feature-server-rhel9:1786110051 | RHSA-2026:53261 |
| Red Hat OpenShift AI 3.3 | rhoai/odh-feature-server-rhel9:1786110033 | RHSA-2026:53263 |
| Red Hat OpenShift AI 3.4 | rhoai/odh-feature-server-rhel9:1786107278 | RHSA-2026:53262 |
| Red Hat OpenShift AI 3.4 | rhoai/odh-feature-server-rhel9:1787068065 | RHSA-2026:60520 |
Frequently Asked Questions
Is CVE-2026-18948 in your dependencies?
Find it across PyPI, including transitive dependencies.