CVE-2026-42557

CRITICALNVD 9.69.6—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.6 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 69% 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
9.6EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.6Exploit: None knownExposed: 0

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

jupyterlab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. Prior to 4.5.7, JupyterLab's HTML sanitizer allowlists data-commandlinker-command and data-commandlinker-args on button elements, while CommandLinker listens for all click events on document.body and executes the named command without checking whether the element came from trusted JupyterLab UI. A notebook with a pre-saved HTML cell output containing a deceptive button can trigger arbitrary JupyterLab commands - including arbitrary code execution - on a single user click, without any code being submitted for execution by the user. This vulnerability is fixed in 4.5.7.

CVSS v3
9.6
EG Score
9.6(medium)
EG Risk
43(Track)
EG Risk 43/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity96% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
28%
KEV
Not listed

Published

May 13, 2026

Last Modified

July 22, 2026

Advisory Details (1)

Auto-updated May 13, 2026
Patch available. Sources: github.
github Patch Available

Command linker attributes in HTML enable one-click command execution from untrusted content · Advisory · jupyterlab/jupyterlab · GitHub

https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg

Vendor Advisories for CVE-2026-42557(2)

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

Affected Packages

(2 across 1 ecosystem)
PyPI(2)
PackageVulnerable rangeFixed inDependents
jupyterlab0.0.1 ... 4.5.6 (584 versions)4.5.7—
notebook7.0.0 ... 7.5.5 (69 versions)7.5.6—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 36× 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. 2026-07-26 14:54 UTCEPSS rescore
  2. 2026-07-26 14:54 UTCEPSS rescore
  3. 2026-07-25 14:18 UTCEPSS rescore
  4. 2026-07-24 14:17 UTCEPSS rescore
  5. 2026-07-23 14:18 UTCEPSS rescore
  6. 2026-07-23 03:11 UTCEG score recompute
  7. 2026-07-22 14:08 UTCEPSS rescore
  8. 2026-07-21 15:24 UTCEPSS rescore
  9. 2026-07-20 17:08 UTCEPSS rescore
  10. 2026-07-19 14:31 UTCEPSS rescore
  11. 2026-07-19 02:29 UTCEPSS rescore
  12. 2026-07-18 10:04 UTCEPSS rescore
  13. 2026-07-18 03:29 UTCOSV refresh
  14. 2026-07-16 17:03 UTCEPSS rescore
  15. 2026-07-15 16:57 UTCEPSS rescore
  16. 2026-07-15 02:25 UTCNVD updateCVSS v3 → 9.6 · severity → CRITICAL
  17. 2026-07-15 02:00 UTCEPSS rescore
  18. 2026-07-13 22:30 UTCEPSS rescore
  19. 2026-07-13 06:13 UTCEPSS rescore
  20. 2026-07-12 05:46 UTCEPSS rescore
  21. 2026-07-11 08:27 UTCEPSS rescore
  22. 2026-07-09 19:10 UTCEPSS rescore
  23. 2026-07-08 15:15 UTCEPSS rescore
  24. 2026-07-07 13:46 UTCEPSS rescore
  25. 2026-07-07 12:11 UTCMITRE cvelistV5CVSS v3 → 8.8 · severity → HIGH
Show 65 more
  1. 2026-07-06 16:27 UTCEPSS rescore
  2. 2026-07-06 16:27 UTCEPSS rescore
  3. 2026-07-06 02:23 UTCEPSS rescore
  4. 2026-07-06 02:23 UTCEPSS rescore
  5. 2026-07-05 02:30 UTCEPSS rescore
  6. 2026-07-04 06:31 UTCEPSS rescore
  7. 2026-07-01 15:06 UTCEPSS rescore
  8. 2026-06-30 23:22 UTCEPSS rescore
  9. 2026-06-29 14:06 UTCEPSS rescore
  10. 2026-06-28 14:07 UTCEPSS rescore
  11. 2026-06-28 04:56 UTCEPSS rescore
  12. 2026-06-27 03:08 UTCEPSS rescore
  13. 2026-06-25 13:49 UTCEPSS rescore
  14. 2026-06-25 13:49 UTCEPSS rescore
  15. 2026-06-24 14:05 UTCEPSS rescore
  16. 2026-06-23 21:33 UTCEPSS rescore
  17. 2026-06-22 14:25 UTCEPSS rescore
  18. 2026-06-22 14:25 UTCEPSS rescore
  19. 2026-06-21 14:56 UTCEPSS rescore
  20. 2026-06-21 14:56 UTCEPSS rescore
  21. 2026-06-21 01:59 UTCEPSS rescore
  22. 2026-06-19 19:25 UTCEPSS rescore
  23. 2026-06-18 17:52 UTCEPSS rescore
  24. 2026-06-18 17:52 UTCEPSS rescore
  25. 2026-06-17 17:53 UTCEPSS rescore
  26. 2026-06-16 17:52 UTCEPSS rescore
  27. 2026-06-15 17:49 UTCEPSS rescore
  28. 2026-06-13 23:00 UTCEPSS rescore
  29. 2026-06-12 23:12 UTCEPSS rescore
  30. 2026-06-12 23:12 UTCEPSS rescore
  31. 2026-06-11 14:00 UTCEPSS rescore
  32. 2026-06-10 22:18 UTCEPSS rescore
  33. 2026-06-10 13:22 UTCEPSS rescore
  34. 2026-06-10 13:22 UTCEPSS rescore
  35. 2026-06-08 14:17 UTCEPSS rescore
  36. 2026-06-08 14:17 UTCEPSS rescore
  37. 2026-06-07 15:25 UTCEPSS rescore
  38. 2026-06-07 15:25 UTCEPSS rescore
  39. 2026-06-06 13:47 UTCEPSS rescore
  40. 2026-06-06 13:47 UTCEPSS rescore
  41. 2026-06-05 22:47 UTCEPSS rescore
  42. 2026-06-05 06:10 UTCEPSS rescore
  43. 2026-06-05 06:10 UTCEPSS rescore
  44. 2026-06-04 13:12 UTCEPSS rescore
  45. 2026-06-04 13:12 UTCEPSS rescore
  46. 2026-06-03 05:47 UTCEG score recompute▲ 1.00
  47. 2026-06-02 20:13 UTCEPSS rescore
  48. 2026-06-01 13:52 UTCEPSS rescore
  49. 2026-06-01 13:52 UTCEPSS rescore
  50. 2026-05-31 22:30 UTCEPSS rescore
  51. 2026-05-31 22:30 UTCEPSS rescore
  52. 2026-05-31 00:16 UTCEPSS rescore
  53. 2026-05-31 00:16 UTCEPSS rescore
  54. 2026-05-29 13:44 UTCEPSS rescore
  55. 2026-05-29 13:44 UTCEPSS rescore
  56. 2026-05-28 13:44 UTCEPSS rescore
  57. 2026-05-28 13:44 UTCEPSS rescore
  58. 2026-05-27 13:40 UTCEPSS rescore
  59. 2026-05-27 13:40 UTCEPSS rescore
  60. 2026-05-26 13:44 UTCEPSS rescore
  61. 2026-05-26 07:18 UTCEPSS rescore
  62. 2026-05-26 07:18 UTCEPSS rescore
  63. 2026-05-20 12:31 UTCEG score recompute
  64. 2026-05-20 11:22 UTCEPSS rescore
  65. 2026-05-20 11:22 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-42557?
CVE-2026-42557 is a critical vulnerability published on May 13, 2026. jupyterlab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. Prior to 4.5.7, JupyterLab's HTML sanitizer allowlists data-commandlinker-command and data-commandlinker-args on button elements, while CommandLinker listens for all click…
When was CVE-2026-42557 disclosed?
CVE-2026-42557 was first published in the National Vulnerability Database on May 13, 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-2026-42557 actively exploited?
CVE-2026-42557 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 72.5% of all scored CVEs.
What is the CVSS score of CVE-2026-42557?
CVE-2026-42557 has a CVSS v3 base score of 9.6 (NVD).
How do I remediate CVE-2026-42557?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-42557, 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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