Security readout for executives and security teams
Plain-English summary
Feast versions before 0.63.0 can let a remote attacker take control of an exposed registry server without authentication. Successful exploitation runs code as the Feast service account, threatening stored data, connected systems, and service availability.
Executive priority
Prioritize emergency remediation for internet-facing or broadly reachable registry servers. Complete rapid inventory elsewhere and upgrade promptly. Because exploitation requires no privileges or user interaction and can compromise confidentiality, integrity, and availability, network isolation alone should be considered temporary risk reduction.
Technical view
A crafted ApplyFeatureView gRPC request can supply an OnDemandFeatureView whose base64-decoded user_defined_function.body reaches dill.loads() before authorization. Unsafe Python deserialization permits attacker-controlled object reconstruction and arbitrary code execution with the Feast service account’s privileges. This is CWE-502 with CVSS 3.1 score 9.8.
Likely exposure
Exposure is highest where a Feast registry server below 0.63.0 accepts gRPC requests from untrusted networks or unauthorized clients. Internal-only deployments remain vulnerable if an attacker gains network access. The bundle does not establish which downstream distributions or configurations expose this service by default.
Exploitation context
The public disclosure includes technical and exploit-related material, making reproduction more plausible. However, the supplied record is not in KEV, and no cited evidence confirms active exploitation in the wild. Treat this as readily exploitable exposure, not a confirmed campaign.
Researcher notes
Focus defensive review on ApplyFeatureView processing, OnDemandFeatureView user-defined functions, authorization ordering, and Python deserialization boundaries. Preserve relevant gRPC and host telemetry before remediation. The bundle identifies the vulnerable data path and patch commit but provides no evidence of observed indicators or active campaigns.
Mitigation direction
- Upgrade Feast to version 0.63.0 or a later vendor-supported release.
- Until upgraded, restrict registry gRPC access to explicitly trusted clients and networks.
- Minimize the Feast service account’s permissions and access to sensitive systems.
- Review Feast and Red Hat guidance for deployment-specific remediation requirements.
Validation and detection
- Inventory Feast versions and identify every registry server below 0.63.0.
- Determine whether registry gRPC endpoints are reachable by untrusted or unauthorized clients.
- Verify the deployed package includes the vendor patch associated with version 0.63.0.
- Review logs for unexpected ApplyFeatureView requests or unusual Feast service-account activity.
- After remediation, confirm unauthorized clients cannot invoke registry modification operations.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-502: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-56121 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
3 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N——VulnCheckCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H2.85.9redhat-SADPVulnerability scoring details
Base CVSS 4.0 score
9.3CriticalVector: 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
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-06-24T16:00:57.361Z: Reported to Red Hat.
- 2026-06-24T14:49:11.490Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- Huntr DisclosureCVE reference, VulnCheck · technical-description, exploit
- Release NotesCVE reference, VulnCheck · release-notes
- Patch CommitCVE reference, VulnCheck · patch
- https://www.vulncheck.com/advisories/feast-unauthenticated-rce-via-applyfeatureview-grpc-deserializationCVE reference, VulnCheck · third-party-advisory
- https://access.redhat.com/security/cve/CVE-2026-56121CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2492229CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-56121.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:60520CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Deserialization of Untrusted Data
Deserialization of Untrusted Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.