PYSEC-2026-1479

### Impact

`jupyter_scheduler` is missing an authentication check in Jupyter Server on an API endpoint (`GET /scheduler/runtime_environments`) which lists the names of the Conda environments on the server. In affected versions, `jupyter_scheduler` allows an unauthenticated user to obtain the list of Conda environment names on the server. This reveals any information that may be present in a Conda environment name.

This issue does **not** allow an unauthenticated third party to read, modify, or enter the Conda environments present on the server where `jupyter_scheduler` is running. This issue only reveals the list of Conda environment names.

Impacted versions: `>=1.0.0,<=1.1.5 ; ==1.2.0 ; >=1.3.0,<=1.8.1 ; >=2.0.0,<=2.5.1`

### Patches

* `jupyter-scheduler==1.1.6` * `jupyter-scheduler==1.2.1` * `jupyter-scheduler==1.8.2` * `jupyter-scheduler==2.5.2`

### Workarounds

Server operators who are unable to upgrade can disable the `jupyter-scheduler` extension with:

``` jupyter server extension disable jupyter-scheduler ```

### References

If you have any questions or comments about this advisory we ask that you contact AWS/Amazon Security via our vulnerability reporting page [1] or directly via email to [aws-security@amazon.com](mailto:aws-security@amazon.com). Please do not create a public GitHub issue.

[1] Vulnerability reporting page: https://aws.amazon.com/security/vulnerability-reporting