XSS in Jupyter Jupyter_server
CVE-2026-44727
Jupyter Server is the backend for Jupyter web applications. Prior to 2.20, the nbconvert HTTP handlers in jupyter_server render user-authored notebook HTML under the Jupyter origin without a sandbox directive in their Content-Security-Poli…
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.003 (22.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.
Affected products
- Jupyter Jupyter_server
- Jupyter-server Jupyter_server — versions < 2.20
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Patch, Mitigation, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-44727?
- CVE-2026-44727 is a medium-severity vulnerability in Jupyter Jupyter_server, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-06-22.
- How severe is CVE-2026-44727?
- Medium severity. CVSS v3 base score is 5.4 out of 10.