Path escape in BuildKit lets clients set extended attributes
Key facts
- Attack vector
- Local
- Privileges required
- High
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · None
- Fix status
- Partial Red Hat: 1 fixed, 20 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat.
Summary
Moby BuildKit versions prior to v0.34.1 are affected. A malicious client with access to the BuildKit control APIs can submit a build request that sets an extended attribute on a file outside the BuildKit state directory (CWE-61). Extended attributes in the trusted and security namespaces may also be set, potentially giving a program on the host elevated privileges. The issue affects build services that accept build requests from untrusted users.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
In BuildKit versions prior to v0.34.1, a malicious client with access to the BuildKit control APIs can submit a build request that sets an extended attribute on a file outside the BuildKit state directory. Extended attributes in the trusted. or security. namespaces may also be set, potentially giving a program on the host elevated privileges. This issue affects build services that accept build requests from untrusted users. The issue is fixed in v0.34.1.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| moby | BuildKit | before 0.34.1 | 0.34.1 | Patch available | CNA |
- BuildKit Vendormoby Affected before 0.34.1 Fixed in 0.34.1 Patch available CNA
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mobyproject:buildkit:*:*:*:*:*:*:*:* | — | — | Mobyproject |
- cpe:2.3:a:mobyproject:buildkit:*:*:*:*:*:*:*:* Versions — — ·Mobyproject
Remediation
Moby BuildKit is fixed in v0.34.1. Red Hat fixes Red Hat Hardened Images in RHSA-2026:95611. Red Hat lists no fix available for DPU kit for NVIDIA, NVIDIA JetPack 7 for RHEL, OpenShift Developer Tools and Services, OpenShift Source-to-Image (S2I), Pen Drive Powered by Red Hat Lightspeed and other products.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA BuildKit (Moby) Fixed in 0.34.1
Red Hat 1 advisory
- RHSA-2026:95611 Released 2026-11-05 · Red Hat rating ImportantRed Hat Hardened Images RPMs Security Update
- Red Hat Hardened Images podman-5:6.1.4-1.3.hum1@aarch64, podman-5:6.1.4-1.3.hum1@s390x, podman-5:6.1.4-1.3.hum1@src +12
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| DPU kit for NVIDIA | Affected | No fix yet |
| NVIDIA JetPack 7 for RHEL | Affected | No fix yet |
| OpenShift Developer Tools and Services | Affected | No fix yet |
| OpenShift Source-to-Image (S2I) | Affected | No fix yet |
| Pen Drive Powered by Red Hat Lightspeed | Affected | No fix yet |
| Red Hat Ansible Automation Platform 2 | Affected | No fix yet |
| Red Hat Build of Podman Desktop | Affected | No fix yet |
| Red Hat Ceph Storage 9 | Affected | No fix yet: Fix deferred |
| Red Hat Certification Program for Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat Developer Hub 1 | Affected | No fix yet |
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 8 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet |
| Red Hat OpenShift Dev Spaces | Affected | No fix yet |
| Red Hat OpenShift GitOps | Affected | No fix yet |
| Red Hat OpenStack Platform 18.0 | Affected | No fix yet |
| Red Hat Openshift Data Foundation 4 | Affected | No fix yet |
| Red Hat Trusted Artifact Signer | Affected | No fix yet |
| Red Hat Web Terminal | Affected | No fix yet |
| Red Hat Hardened Images | Fixed | RHSA-2026:95611 |
Not affected: 24 products
- Assisted Installer for Red Hat OpenShift Container Platform 2
- Compliance Operator
- Confidential Compute Attestation
- Custom Metric Autoscaler operator for Red Hat Openshift
- Kernel Module Management Operator for Red Hat Openshift
- Logical Volume Manager Storage
- Migration Toolkit for Applications 8
- Migration Toolkit for Containers
- Migration Toolkit for Virtualization
- Multicluster Engine for Kubernetes
- Node HealthCheck Operator
- OpenShift Lightspeed
- OpenShift Serverless
- OpenShift Service Mesh 3
- Red Hat Advanced Cluster Management for Kubernetes 2
- Red Hat Build of Kueue
- Red Hat Edge Manager 1
- Red Hat Hardened Images
- Red Hat OpenShift AI (RHOAI)
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
- Red Hat OpenShift Virtualization 4
- Red Hat OpenShift Virtualization 5
- Red Hat Quay 3
Timeline
- 2026-11-03 Threatist record created from CVE-2026-121520
- 2026-11-04 Affected versions changed · Red Hat
- 2026-11-04 CVSS score added · Red Hat
- 2026-11-05 Affected versions changed · Red Hat
- 2026-11-06 Fix available: Red Hat Hardened Images · Red Hat
- 2026-11-06 Fix available: RHSA-2026:95611 · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 CISA SSVC decision points changed
References
More moby vulnerabilities
- TI-2026-14229 Tar extraction in moby/go-archive can write outside the destination directory via link following CVSS 4.0HIGH 7.1
- TI-2021-12512 Moby HyperKit uninitialized memory use in virtio-sock pci_vtsock_proc_tx CVSS 3.1HIGH 7.1
- TI-2024-27462 Moby authz zero length regression CVSS 3.1CRITICAL 10.0
- TI-2024-15672 BuildKit interactive containers API does not validate entitlements check CVSS 3.1CRITICAL 9.8
- TI-2024-15671 BuildKit possible host system access from mount stub cleaner CVSS 3.1CRITICAL 10.0
- TI-2026-26365 Moby: AuthZ plugin bypass with oversized request body CVSS 3.1HIGH 8.8
Sources
- CVE-2026-121520 · CVE Program
- CVE-2026-121520 · NVD
- FIRST EPSS
- CVE-2026-121520 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences