CVE•Published 2026-06-22•Modified 2026-07-22•0 articles on news•5 live references•NVD data

CVE-2026-44727Jupyter · Jupyter_server

Vulnerability data via NVD (ingested)

CVSS v3.1

5.4

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS percentile

Exploit Prediction Scoring System · top 87% of all CVEs

Weaknesses (CWE)

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')CWE-1021Improper Restriction of Rendered UI Layers or Frames

Description

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-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. This vulnerability is fixed in 2.20.

Timeline

Published 2026-06-22

Modified 2026-07-22

External references

NVD MITRE Exploit-DB GitHub PoC VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag2,391 hosts

vuln:CVE-2026-44727

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"Jupyter Jupyter Server"

All exposed Jupyter Jupyter Server instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"Jupyter Server"

HTTP body or banner mentions "Jupyter Server" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-44727