CVE-2026-6658

MEDIUMPre-NVD 5.45.4—
EchelonGraph scoreHIGH confidence

Score 5.4 from GitHub Security Advisory published 2026-06-26. a secondary CVSS source baseline 5.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
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.

A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized text/vnd.mermaid output in HTML exports. The data_mermaid block in share/templates/lab/base.html.j2 renders text/vnd.mermaid cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the `` tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export.

CVSS v3
5.4
EG Score
5.4(high)
EPSS
3.2%
KEV
Not listed

Published

June 26, 2026

Last Modified

June 26, 2026

Advisory Details (1)

Auto-updated Jun 26, 2026
No patch confirmed yet.
generic

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Vendor Advisories for CVE-2026-6658(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 22× in last 7d / 34× 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. 2026-07-06 14:57 UTCEG score recompute
  2. 2026-07-06 14:57 UTCGHSA enrichment
  3. 2026-07-06 02:23 UTCEPSS rescore
  4. 2026-07-06 02:23 UTCEPSS rescore
  5. 2026-07-05 14:31 UTCEG score recompute
  6. 2026-07-05 14:31 UTCGHSA enrichment
  7. 2026-07-05 02:31 UTCEPSS rescore
  8. 2026-07-05 02:30 UTCEPSS rescore
  9. 2026-07-04 14:13 UTCEG score recompute
  10. 2026-07-04 14:13 UTCGHSA enrichment
  11. 2026-07-04 06:31 UTCEPSS rescore
  12. 2026-07-04 06:31 UTCEPSS rescore
  13. 2026-07-03 13:54 UTCEG score recompute
  14. 2026-07-03 13:54 UTCGHSA enrichment
  15. 2026-07-02 13:35 UTCEG score recompute
  16. 2026-07-02 13:35 UTCGHSA enrichment
  17. 2026-07-01 15:07 UTCEPSS rescore
  18. 2026-07-01 13:17 UTCEG score recompute
  19. 2026-07-01 13:17 UTCGHSA enrichment
  20. 2026-06-30 23:22 UTCEPSS rescore
  21. 2026-06-30 12:54 UTCEG score recompute
  22. 2026-06-30 12:54 UTCGHSA enrichment
  23. 2026-06-29 14:06 UTCEPSS rescore
  24. 2026-06-29 12:36 UTCEG score recompute
  25. 2026-06-29 12:36 UTCGHSA enrichment
Show 9 more
  1. 2026-06-28 14:07 UTCEPSS rescore
  2. 2026-06-28 12:17 UTCEG score recompute
  3. 2026-06-28 12:17 UTCGHSA enrichment
  4. 2026-06-28 04:56 UTCEPSS rescore
  5. 2026-06-27 11:58 UTCEG score recompute
  6. 2026-06-27 11:58 UTCGHSA enrichment
  7. 2026-06-27 03:08 UTCEPSS rescore
  8. 2026-06-26 11:39 UTCEG score recompute
  9. 2026-06-26 11:39 UTCNVD updatefirst tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-6658?
CVE-2026-6658 is a medium vulnerability published on June 26, 2026. A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized text/vnd.mermaid output in HTML exports. The data_mermaid block in share/templates/lab/base.html.j2 renders text/vnd.mermaid cell output directly into HTML without escaping, enabling…
When was CVE-2026-6658 disclosed?
CVE-2026-6658 was first published in the National Vulnerability Database on June 26, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-6658 actively exploited?
CVE-2026-6658 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 3.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-6658?
CVE-2026-6658 has a CVSS v3 base score of 5.4 (NVD).
How do I remediate CVE-2026-6658?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-6658, 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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