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Vulnerability record · CVE-2026-56121 · published 24 June 2026

CVE-2026-56121: Deserialization of untrusted data vulnerability

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.

9.3 CVSS 4.0 Critical EPSS 1.4% · top 28.5% CWE-502 · Deserialization of untrusted data Deferred
9.3CVSS 4.0 base score
1.4%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
8References
28 Aug 2026Last modified by NVD

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.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/feast-dev/feast/commit/835cda8e2c1359f1f496ad72701dbd6a73bdb25a
https://github.com/feast-dev/feast/releases/tag/v0.63.0
https://huntr.com/bounties/d64b8111-180b-46ba-afa3-c877fda2ede6
https://www.vulncheck.com/advisories/feast-unauthenticated-rce-via-applyfeatureview-grpc-deserialization
https://access.redhat.com/errata/RHSA-2026:60520
https://access.redhat.com/security/cve/CVE-2026-56121
https://bugzilla.redhat.com/show_bug.cgi?id=2492229
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-56121.json

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Source: NIST National Vulnerability Database (record CVE-2026-56121), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.