CVE-2026-56121
Feast < 0.63.0 Unauthenticated RCE via ApplyFeatureView gRPC Deserialization
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
9.3
Feast < 0.63.0 Unauthenticated RCE via ApplyFeatureView gRPC Deserialization
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.
- Record
CVE-2026-56121- CVSS 4.0
- 9.3 Critical
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 - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 3.1
- 8.8 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-502, CWE-502
- Updated
- 2026-11-02
EUVDEUVD-2026-38801
9.3
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.
- Record
EUVD-2026-38801- CVSS 4.0
- 9.3 Critical
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-q63x-9pfm-mjx4
9.3
Feast vulnerable to unsafe deserialization RCE in registry server via UDF proto
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.
- Record
GHSA-q63x-9pfm-mjx4- CVSS 4.0
- 9.3 Critical
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 - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-502
- Updated
- 2026-11-03
NVD
9.3
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.
- Record
CVE-2026-56121- CVSS 4.0
- 9.3 Critical
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 - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 3.1
- 8.8 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-502
- Updated
- 2026-11-02
OSV
9.3
Feast < 0.63.0 Unauthenticated RCE via ApplyFeatureView gRPC Deserialization
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.
- Record
CVE-2026-56121- CVSS 4.0
- 9.3 Critical
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 - Weakness
- CWE-502
- Updated
- 2026-11-02
OSVGHSA-q63x-9pfm-mjx4
9.3
Feast vulnerable to unsafe deserialization RCE in registry server via UDF proto
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.
- Record
GHSA-q63x-9pfm-mjx4- CVSS 4.0
- 9.3 Critical
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 - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-502
- Updated
- 2026-11-03
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
feastPyPI |
before 0.63.0 | 0.63.0 |
feastPyPI |
before 0.63.0, plus listed versions 0.1.00.1.0.post00.1.20.1.2.post00.1.2.post1 Show 45 moreShow less0.10.00.10.10.10.1rc10.10.1rc30.10.20.10.30.10.40.10.50.10.60.10.70.10.80.11.00.12.00.12.10.13.00.14.00.14.10.15.00.15.10.16.00.16.10.17.00.18.00.18.10.19.00.19.10.19.20.19.30.19.40.20.00.20.10.20.20.21.00.21.10.21.20.21.30.22.00.22.10.22.20.22.30.22.40.23.00.23.10.23.20.24.0 |
0.63.0 |
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| PoC in GitHub | BiiTts/CVE-2026-56121-Feast-Unauth-RCE | 2026-06-30 |
| PoC in GitHub | 0xdak/CVE-2026-56121_exploit | 2026-07-23 |
| PoC in GitHub | joaovicdev/EXPLOIT-CVE-2026-56121 | 2026-08-30 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, references | OSV | |
| affected, exploits, facts | GitHub Advisories | |
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV, PoC in GitHub |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-56121 is a critical vulnerability (CVSS 9.3) in Feast-dev Feast, published June 24, 2026. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 1.41%, the 72nd percentile. Fixed in feast 0.63.0.
References
huntr.com/bounties/d64b8111-180b-46ba-afa3-c877fda2ede6
github.com/feast-dev/feast/releases/tag/v0.63.0
github.com/feast-dev/feast/commit/835cda8e2c1359f1f496ad72701dbd6a73bdb25a
vulncheck.com/advisories/feast-unauthenticated-rce-via-applyfeatureview-grpc-deserialization
access.redhat.com/security/cve/CVE-2026-56121
bugzilla.redhat.com/show_bug.cgi?id=2492229
Show 6 moreShow less
Left out here: 97 versions. The JSON record has them.