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Public proof of concept

CVE-2026-56121

A public proof of concept exists; no exploitation attested.

  • Published2026-06-24
  • WeaknessCWE-502

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-06-2416:16CVE publishedNVD
  2. 2026-10-2319:23First public proof of conceptPoC-in-GitHub

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-56121?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-56121?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-56121 yet.

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

read 2026-10-23 19:25 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
3 repositories, unverifiedBiiTts/CVE-2026-56121-Feast-Unauth-RCE0xdak/CVE-2026-56121_exploitjoaovicdev/EXPLOIT-CVE-2026-56121
PoC-in-GitHub

Sources

  • NVDCVE recordread 2026-10-23
  • CISA-ADPSSVC decisionpoc2026-06-25
  • OpenCVESSVC decisionpoc—
  • CNACVSS 4.09.3read 2026-10-23
  • CNACVSS 3.19.8read 2026-10-23
  • CNAweakness (CWE)CWE-502read 2026-10-23
  • FIRST EPSSEPSS score1.4 %2026-10-23
  • PoC-in-GitHubproof of concept3read 2026-10-23

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 4.0 vector
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:X/V:X/RE:X/U:X
Published
2026-06-24
Last Modified
2026-08-28
NVD status
Deferred

Frequently asked questions

What is CVE-2026-56121?

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.

Is CVE-2026-56121 actively exploited?

A proof-of-concept exploit exists for CVE-2026-56121, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-56121?

CVE-2026-56121 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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