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CVE-2026-56121: Feast Unsafe Deserialization Enables Remote Code Execution via gRPC Registry

Feast versions before 0.63.0 deserialize a field of OnDemandFeatureView specs with dill.loads() before any authorization check, which can allow remote code execution through the registry server. The record rates it critical, with CVSS 3.1 base score 9.8 from VulnCheck. No confirmed exploitation appears in the sources consulted, and the CVE is not listed in CISA KEV.

Published Oct 13, 2026 · Updated Oct 13, 2026 · Ler em português

Overview

CVE-2026-56121 is a deserialization flaw (CWE-502) in Feast, an open-source feature store. According to the record, the registry server decodes a field of an OnDemandFeatureView spec and passes it to dill.loads() before authorization is checked. The record describes the issue as affecting Feast versions before 0.63.0.

Impact

  • The record states that unauthenticated or unauthorized attackers may achieve remote code execution.
  • Code would run as the feast service account.
  • The record assigns CVSS 3.1 base score 9.8 (vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) with critical severity. It also lists a CVSS 4.0 score of 9.3 from the same CNA.
  • Confidentiality, integrity and availability impacts are rated high in the CVSS 3.1 vector.

Affected products and versions

  • The record describes Feast before 0.63.0 as affected.
  • The structured affected and fixes fields in the record are empty, so no product list or fixed-version metadata is available beyond the description.
  • A release tagged v0.63.0 is referenced in the record, which suggests that version is the relevant upgrade target. This is an inference from the description and the reference list.

Exploitation status

  • The CISA KEV entry is not listed in the record.
  • No confirmed exploitation in the wild appears in the sources consulted.
  • EPSS and SSVC data are not present in the record.

Remediation and mitigation

  • Review the Feast version in use and plan an upgrade to 0.63.0 or later, consistent with the release referenced in the record.
  • Consult the vendor and CNA advisories linked in the references for the authoritative fix and guidance.
  • Until patched, limit network exposure of the registry gRPC endpoint to trusted clients and internal networks only.
  • Run the feast service with least-privilege permissions so that a compromise has a smaller blast radius.
  • Treat registry access as sensitive and enforce authentication and authorization controls at the network and platform layers where possible.

Detection guidance

  • Monitor registry server logs for unusual gRPC requests, especially from unknown sources or at unexpected times.
  • Review stored OnDemandFeatureView definitions for unexpected or unusually large encoded content in the user-defined function field.
  • Watch for unexpected child processes, outbound connections or file changes originating from the feast service account.
  • Alert on authentication or authorization anomalies around the registry endpoint.

Limitations of the available information

  • The record does not include structured affected version ranges, fixed-version metadata, or KEV due dates.
  • The CVSS 3.1 score of 8.8 from a second provider is listed without a named source, so its context is unknown.
  • The record does not state precisely which Feast release introduced the flaw.
  • The sources consulted do not confirm whether public exploit code exists; this analysis does not provide any exploitation detail.

Frequently asked questions

What is the core problem in CVE-2026-56121?

According to the record, Feast before 0.63.0 decodes and deserializes a field of an OnDemandFeatureView spec before checking authorization, which is an unsafe deserialization issue.

Is this vulnerability known to be actively exploited?

The record does not list it in CISA KEV, and no confirmed exploitation in the wild appears in the sources consulted.

What should administrators do first?

Identify Feast deployments below 0.63.0, plan an upgrade consistent with the referenced release, and limit network exposure of the registry endpoint until patched.

This analysis was drafted with AI assistance from verified source data and automatically checked against it.