CVE-2026-56121 Feast < 0.63.0 Unauthenticated RCE via ApplyFeatureView gRPC Deserialization
Unauthenticated attackers can execute arbitrary code on Feast registry servers via unsafe deserialization in gRPC requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-56121?
CVE-2026-56121 is a critical unsafe deserialization vulnerability in feast-dev feast, published on 24 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-502
Which versions are affected by CVE-2026-56121?
How do I fix CVE-2026-56121?
No fix has been published for CVE-2026-56121 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-56121 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-56121 exists.
Public exploit code: 3 proofs of concept on GitHub.
Sources
Also known as GHSA-q63x-9pfm-mjx4.