CVE-2026-44727Jupyter Server is the backend for Jupyter web applications.
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 5.4 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
- Weakness (CWE)
- CWE-79, CWE-1021
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Modified
- Record last updated
- Aug 28, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
jupyter jupyter_server jupyter:jupyter_server | before 2.20.0 | NVD |
References
- https://github.com/jupyter-server/jupyter_server/commit/6cbee8d65e71abac851c4492fea987ad080580bdpatch
- https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-fcw5-x6j4-ccmpmitigation, patch, vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:43038
- https://access.redhat.com/errata/RHSA-2026:60520
- https://access.redhat.com/security/cve/CVE-2026-44727
- https://bugzilla.redhat.com/show_bug.cgi?id=2491516
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44727.json
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.