How severe is CVE-2026-56121?

CVE-2026-56121 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-56121 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-56121?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-56121 have an EU (EUVD) identifier?

Yes. CVE-2026-56121 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38801.

When was CVE-2026-56121 published?

CVE-2026-56121 was published on 2026-06-24 and last updated on 2026-06-30.

CVE-2026-56121

CVE-2026-56121 is a critical-severity vulnerability with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-502.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v4: 9.3
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-38801
Weakness: CWE-502
Published: 2026-06-24
Last modified: 2026-06-30

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.

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.
How severe is CVE-2026-56121?: CVE-2026-56121 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-56121 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-56121?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-56121 have an EU (EUVD) identifier?: Yes. CVE-2026-56121 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38801.
When was CVE-2026-56121 published?: CVE-2026-56121 was published on 2026-06-24 and last updated on 2026-06-30.

References

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