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Description

Feast before 0.63.0 contains an unsafe deserialization vulnerability that allows unauthenticated or unauthorized attackers to achieve remote code execution by sending a crafted gRPC request to the registry server. The user_defined_function.body field of an OnDemandFeatureView spec is decoded from base64 and passed to dill.loads() before any authorization check is performed, enabling attackers to embed a malicious serialized Python object with an arbitrary __reduce__ method to execute OS commands as the feast service account.

PUBLISHED Reserved 2026-06-18 | Published 2026-06-24 | Updated 2026-06-24 | Assigner VulnCheck




CRITICAL: 9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CRITICAL: 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Problem types

Deserialization of Untrusted Data

Product status

Default status
affected

Any version before 0.63.0
affected

Credits

Tanguy Snoeck finder

References

huntr.com/bounties/d64b8111-180b-46ba-afa3-c877fda2ede6 (Huntr Disclosure) technical-description exploit

github.com/feast-dev/feast/releases/tag/v0.63.0 (Release Notes) release-notes

github.com/...ommit/835cda8e2c1359f1f496ad72701dbd6a73bdb25a (Patch Commit) patch

www.vulncheck.com/...a-applyfeatureview-grpc-deserialization third-party-advisory

cve.org (CVE-2026-56121)

nvd.nist.gov (CVE-2026-56121)

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