Security Digest · Vulnerability record
CVE-2026-44181: Jupyter Enterprise Gateway: Jinja2 Template Server Side Template Injection resulting in Remote Code Execution
Jupyter Enterprise Gateway launches remote Jupyter Notebook kernels across distributed clusters like Apache Spark, Kubernetes, and Docker Swarm.
CVSS 10.0 Critical EPSS 0.8% · p55
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.8%, percentile 55: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 55% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
jupyter_enterprise_gateway(PyPI) >= 2.0.0rc2, < 3.3.0, fixed in 3.3.0. Check your lockfile, including transitive dependencies.
What it is
Jupyter Enterprise Gateway launches remote Jupyter Notebook kernels across distributed clusters like Apache Spark, Kubernetes, and Docker Swarm. In versions 2.0.0rc2 and above, prior to 3.3.0, the environment variables (KERNELXXX) 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. This issue has been fixed in version 3.3.0.
From the GitHub advisory
Summary
The environment variables (KERNELXXX) 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 KERNELPODNAME variable is rendered using Jinja2, allowing for code execution via template expression statements, in this code: https://github.com/jupyter-server/enterprisegateway/blob/152c20f162f2fab700c04c8830ebf8c1e2e2217a/enterprisegateway/services/processproxies/k8s.py#L219-L247
The Jinja2 template for the Kubernetes manifest contains several kernelxxx variables, in addition to kernelpodname discussed above, such as kernelworkingdir that are used when rendering the manifest and are all vectors for SSTI. https://github.com/jupyter-server/enterprisegateway/blob/152c20f162f2fab700c04c8830ebf8c1e2e2217a/etc/kernel-launchers/kubernetes/scripts/kernel-pod.yaml.j2#L77
Weakness type: CWE-1336.
Product: jupyter_enterprise_gateway (PyPI) · Assigned by: GitHub_M · Published: 2026-07-16
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| PyPI | jupyter_enterprise_gateway | >= 2.0.0rc2, < 3.3.0 | 3.3.0 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| jupyter-server | enterprise_gateway | >= 2.0.0rc2, < 3.3.0 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 4.0 | 10 Critical | 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 |
| GitHub | 4.0 | 10.0 | 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 |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Attack requirements: none
- Privileges required: none (no login)
- User interaction: none
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.77% probability of exploitation activity in the next 30 days; percentile 55.
Timeline
- — GitHub-reviewed advisory GHSA-f49j-v924-fx9w published (critical)
- — CVE record published by GitHub_M
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-f49j-v924-fx9w github.com
- CVE.org record CVE-2026-44181 cve.org
- NVD entry CVE-2026-44181 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com