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9.4
Jupyter Server lets malicious notebook steal credentials
published 1 month ago
Summary
The Jupyter Server component that converts notebooks to HTML can display attacker‑crafted content without proper protection. This allows a logged‑in user who opens a specially crafted notebook to have their authentication token and other data stolen, and potentially run code on the server. Apply the latest security update for the python‑jupyter‑server package as soon as possible.
What to do
- Update openeuler python-jupyter-server to version 2.13.0-3.oe2403sp3.
Affected software
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| openEuler:24.03-LTS-SP3 | openeuler | python-jupyter-server |
< 2.13.0-3.oe2403sp3 Fix: upgrade to 2.13.0-3.oe2403sp3
|
Original advisory text
python-jupyter-server security update
The backend for Jupyter web applications
Security Fix(es):
The nbconvert HTTP handlers in jupyter_server render user-authored notebook HTML under the Jupyter origin without a sandbox directive in their `Content-Security-Policy`. Combined with `nbconvert.HTMLExporter`'s default non-sanitizing behavior, a notebook carrying an HTML payload in a display_data output triggers stored XSS with cookie access, full /api/* authority, and kernel RCE. An authenticated victim who navigates to `/nbconvert/html/<path>` containing attacker-authored output can have their token exfiltrated to another domain because it is executed in the Jupyter origin.(CVE-2026-44727)
Security Fix(es):
The nbconvert HTTP handlers in jupyter_server render user-authored notebook HTML under the Jupyter origin without a sandbox directive in their `Content-Security-Policy`. Combined with `nbconvert.HTMLExporter`'s default non-sanitizing behavior, a notebook carrying an HTML payload in a display_data output triggers stored XSS with cookie access, full /api/* authority, and kernel RCE. An authenticated victim who navigates to `/nbconvert/html/<path>` containing attacker-authored output can have their token exfiltrated to another domain because it is executed in the Jupyter origin.(CVE-2026-44727)
References
- https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA... Vendor Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-44727 Vendor Advisory
Internet-facing
14 days
Internal
At next upgrade
- Not known to be exploited
- Needs hands-on effort to exploit (estimated)
- Gives an attacker full control (estimated)
Timeline
Published20 Sep 2026
Updated20 Sep 2026
First seen20 Sep 2026
Sources
OESA-2026-3955 · OSV
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