Deserialization of Untrusted Data Affecting feast package, versions [,0.63.0)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-PYTHON-FEAST-17458831
- published25 Jun 2026
- disclosed24 Jun 2026
- creditTanguy Snoeck
Introduced: 24 Jun 2026
CVE-2026-56121 (opens in a new tab)How to fix?
Upgrade feast to version 0.63.0 or higher.
Overview
feast is a Python SDK for Feast
Affected versions of this package are vulnerable to Deserialization of Untrusted Data in the ApplyFeatureView handler of registry_server.py, which calls FeatureView.from_proto and deserializes the feature view's embedded user-defined function before the apply permission is checked. An attacker can execute arbitrary code on the registry server by sending an ApplyFeatureView request whose feature view carries a malicious serialized UDF, which is deserialized and instantiated during the permission-validation step ahead of authorization. Exploitation requires access to port 6570 (gRPC).
Details
Serialization is a process of converting an object into a sequence of bytes which can be persisted to a disk or database or can be sent through streams. The reverse process of creating object from sequence of bytes is called deserialization. Serialization is commonly used for communication (sharing objects between multiple hosts) and persistence (store the object state in a file or a database). It is an integral part of popular protocols like Remote Method Invocation (RMI), Java Management Extension (JMX), Java Messaging System (JMS), Action Message Format (AMF), Java Server Faces (JSF) ViewState, etc.
Deserialization of untrusted data (CWE-502) is when the application deserializes untrusted data without sufficiently verifying that the resulting data will be valid, thus allowing the attacker to control the state or the flow of the execution.