Remote Code Execution Due to Unsafe Deserialization in Feast by Feast Dev
CVE-2026-56121

9.3CRITICAL

Key Information:

Vendor

Feast-dev

Status
Feast
Vendor
CVE Published:
24 June 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-56121?

An unsafe deserialization vulnerability in Feast prior to version 0.63.0 enables unauthorized parties to execute arbitrary code remotely. This flaw arises from the mishandling of the user_defined_function.body field within the OnDemandFeatureView specification. The field is decoded from base64 and processed through dill.loads() without any initial authorization checks. Consequently, attackers can inject malicious Python objects, taking advantage of the reduce method to execute system commands under the privileges of the Feast service account, posing significant security risks.

Affected Version(s)

feast 0

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-56121 - Proof of Concept

References

https://huntr.com/bounties/d64b8111-180b-46ba-afa3-c877fd...
technical-descriptionexploit
https://github.com/feast-dev/feast/releases/tag/v0.63.0
release-notes
https://github.com/feast-dev/feast/commit/835cda8e2c1359f...
patch

CVSS V4

Score:
9.3
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Tanguy Snoeck
.