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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| feast-dev | feast | < 0.63.0 | 0.63.0 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
GitHub 3 repositories
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0xdak/CVE-2026-56121_exploit ★ 1 · Jul 23, 2026
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joaovicdev/EXPLOIT-CVE-2026-56121 ★ 0 · Aug 30, 2026
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BiiTts/CVE-2026-56121-Feast-Unauth-RCE ★ 0 · Jun 30, 2026
CVE-2026-56121 — Feast <0.63.0 unauthenticated RCE via gRPC registry dill.loads of OnDemandFeatureView UDF (pre-auth). Lab + PoC, verified e2e.
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | feast | < 0.63.0 | 0.63.0 | GHSA-q63x-9pfm-mjx4 |
References
- Huntr Disclosure technical-description exploit
- feast 0.63.0 Release Notes release-notes
- Patch Commit patch
- https://www.vulncheck.com/advisories/feast-unauthenticated-rce-via-applyfeatureview-grpc-deserialization third-party-advisory