Summary
Possible pod name collisions in jupyterhub-kubespawner
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
KubeSpawner
Specify configuration:
for KubeSpawner
from traitlets import default
from kubespawner import KubeSpawner
class PatchedKubeSpawner(KubeSpawner):
@default("pod_name_template")
def _default_pod_name_template(self):
if self.name:
return "jupyter-{username}-{servername}"
else:
return "jupyter-{username}"
@default("pvc_name_template")
def _default_pvc_name_template(self):
if self.name:
return "claim-{username}-{servername}"
else:
return "claim-{username}"
c.JupyterHub.spawner_class = PatchedKubeSpawner
Note for KubeSpawner: this configuration will behave differently before and after the upgrade, so will need to be removed when upgrading. Only apply this configuration while still using KubeSpawner ≤ 0.11.1 and remove it after upgrade to ensure consistent pod and pvc naming.
Changing the name template means pvcs for named servers will have different names. This will result in orphaned PVCs for named servers across Hub upgrade! This may appear as data loss for users, depending on configuration, but the orphaned PVCs will still be around and data can be migrated manually (or new PVCs created manually to reference existing PVs) before deleting the old PVCs and/or PVs.
References
Are there any links users can visit to find out more?
For more information
If you have any questions or comments about this advisory:
- Open an issue in kubespawner
- Email us at [email protected]
Credit: Jining Huang
Impact
What kind of vulnerability is it? Who is impacted?
JupyterHub deployments using:
- KubeSpawner <= 0.11.1 (e.g. zero-to-jupyterhub 0.9.0) and
- enabled named_servers (not default), and
- an Authenticator that allows:
- usernames with hyphens or other characters that require escape (e.g.
user-hyphenoruser@email), and - usernames which may match other usernames up to but not including the escaped character (e.g.
userin the above cases)
- usernames with hyphens or other characters that require escape (e.g.
In this circumstance, certain usernames will be able to craft particular server names which will grant them access to the default server of other users who have matching usernames.
The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.
CVE-2020-15110 has a CVSS score of 6.8 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.12.0); upgrading removes the vulnerable code path.
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.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Has the problem been patched? What versions should users upgrade to?
Patch will be released in kubespawner 0.12 and zero-to-jupyterhub 0.9.1
Frequently Asked Questions
- What is CVE-2020-15110? CVE-2020-15110 is a high-severity incorrect authorization vulnerability in jupyterhub-kubespawner (pip), affecting versions <= 0.11.1. It is fixed in 0.12.0. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
- How severe is CVE-2020-15110? CVE-2020-15110 has a CVSS score of 6.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of jupyterhub-kubespawner are affected by CVE-2020-15110? jupyterhub-kubespawner (pip) versions <= 0.11.1 is affected.
- Is there a fix for CVE-2020-15110? Yes. CVE-2020-15110 is fixed in 0.12.0. Upgrade to this version or later.
- Is CVE-2020-15110 exploitable, and should I be worried? Whether CVE-2020-15110 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-2020-15110 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-2020-15110? Upgrade
jupyterhub-kubespawnerto 0.12.0 or later.