CVE-2026-44727

MEDIUMNVD 5.45.4—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.4 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 87% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
5.4
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.4Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
5.4
EG Score
5.4(medium)
EPSS
13.5%
KEV
Not listed

Published

June 18, 2026

Last Modified

July 22, 2026

Advisory Details (2)

Auto-updated Jun 22, 2026
Patch available. Sources: github_commit, github.
github Patch Available

Stored XSS in `NbconvertFileHandler` / `NbconvertPostHandler` via missing `sandbox` CSP · Advisory · jupyter-server/jupyter_server · GitHub

Affected: v2.20.0, commit

https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-fcw5-x6j4-ccmp
github_commit Patch Available

commit 6cbee8d65e71 (jupyter-server/jupyter_server)

Patch available: jupyter-server/jupyter_server v2.20.0 (contains commit 6cbee8d65e71)

https://github.com/jupyter-server/jupyter_server/commit/6cbee8d65e71abac851c4492fea987ad080580bd

Vendor Advisories for CVE-2026-44727(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
jupyter-server0.0.0 ... 2.9.1 (159 versions)2.20.0—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 37× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 14:08 UTCEPSS rescore
  2. 2026-07-21 15:24 UTCEPSS rescore
  3. 2026-07-20 17:08 UTCEPSS rescore
  4. 2026-07-19 14:31 UTCEPSS rescore
  5. 2026-07-19 02:29 UTCEPSS rescore
  6. 2026-07-18 10:04 UTCEPSS rescore
  7. 2026-07-16 17:03 UTCEPSS rescore
  8. 2026-07-15 16:57 UTCEPSS rescore
  9. 2026-07-15 06:32 UTCEG score recompute▼ 3.60
  10. 2026-07-15 02:26 UTCNVD updateCVSS v3 → 5.4 · severity → MEDIUM
  11. 2026-07-15 02:00 UTCEPSS rescore
  12. 2026-07-13 06:13 UTCEPSS rescore
  13. 2026-07-12 05:46 UTCEPSS rescore
  14. 2026-07-11 08:27 UTCEPSS rescore
  15. 2026-07-09 19:10 UTCEPSS rescore
  16. 2026-07-08 21:39 UTCEG score recompute▲ 3.60
  17. 2026-07-08 15:16 UTCEPSS rescore
  18. 2026-07-08 12:47 UTCMITRE cvelistV5CVSS v3 → 9 · severity → CRITICAL
  19. 2026-07-07 13:46 UTCEPSS rescore
  20. 2026-07-06 16:27 UTCEPSS rescore
  21. 2026-07-06 02:23 UTCEPSS rescore
  22. 2026-07-05 02:30 UTCEPSS rescore
  23. 2026-07-04 06:31 UTCEPSS rescore
  24. 2026-07-01 15:07 UTCEPSS rescore
  25. 2026-06-30 23:22 UTCEPSS rescore
Show 15 more
  1. 2026-06-29 14:06 UTCEPSS rescore
  2. 2026-06-29 14:06 UTCEPSS rescore
  3. 2026-06-28 14:07 UTCEPSS rescore
  4. 2026-06-28 04:56 UTCEPSS rescore
  5. 2026-06-28 04:56 UTCEPSS rescore
  6. 2026-06-27 03:08 UTCEPSS rescore
  7. 2026-06-26 23:10 UTCEG score recompute▼ 3.90
  8. 2026-06-26 19:41 UTCNVD updateCVSS v3 → 5.4 · severity → MEDIUM
  9. 2026-06-25 13:49 UTCEPSS rescore
  10. 2026-06-25 13:49 UTCEPSS rescore
  11. 2026-06-24 14:05 UTCEPSS rescore
  12. 2026-06-23 21:33 UTCEPSS rescore
  13. 2026-06-22 21:40 UTCEG score recompute▲ 9.30
  14. 2026-06-22 21:37 UTCNVD updateCVSS v3 → 9.3 · CVSS v4 → 9.3
  15. 2026-06-18 15:08 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-44727?
CVE-2026-44727 is a medium vulnerability published on June 18, 2026. Jupyter Server is the backend for Jupyter web applications. Prior to 2.20, the nbconvert HTTP handlers in jupyterserver render user-authored notebook HTML under the Jupyter origin without a sandbox directive in their Content-Security-Policy. Combined with nbconvert.HTMLExporter's default…
When was CVE-2026-44727 disclosed?
CVE-2026-44727 was first published in the National Vulnerability Database on June 18, 2026, with the most recent update on July 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-44727 actively exploited?
CVE-2026-44727 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 13.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-44727?
CVE-2026-44727 has a CVSS v3 base score of 5.4 (NVD).
How do I remediate CVE-2026-44727?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-44727, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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