CVE-2026-42557

CRITICALNVD 9.69.6—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.6 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 72% 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

A fix is available — apply it.

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
31%
KEV
Not listed

Published

May 13, 2026

Last Modified

August 28, 2026

Advisory Details (6)

Auto-updated Sep 14, 2026
Patch available. Sources: github, redhat.
redhat
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42557.json
redhat

2477086 – (CVE-2026-42557) CVE-2026-42557 jupyterlab: JupyterLab: Arbitrary code execution via deceptive button in HTML output

https://bugzilla.redhat.com/show_bug.cgi?id=2477086
redhat Patch Available

CVE-2026-42557 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a

https://access.redhat.com/security/cve/CVE-2026-42557
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:60520
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:43038
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(3)

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

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatrhoai/odh-workbench-jupyter-trustyai-cpu-py312-rhel9:17870735932026-08-27redhat
redhatmta/mta-solution-server-rhel9:17841098832026-07-21redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(4 across 3 ecosystems)
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—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
jupyterlab4.0.11+ds1+~cs11.25.27-7 ... 4.4.8+ds1+~3.1.0+~0.16.6+~cs1.4.4-1 (27 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
jupyterlab4.0.11+ds1+~cs11.25.27-7 ... 4.4.8+ds1+~3.1.0+~0.16.6+~cs1.4.4-1 (25 versions)4.4.10+ds1+~3.1.0+~0.16.6+~cs1.4.4-3—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 33× 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.

Showing the most recent 100 of 216 total refreshes for this CVE.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-17 19:31 UTCEPSS rescore
  3. 2026-09-16 16:39 UTCOSV refresh
  4. 2026-09-16 14:08 UTCEPSS rescore
  5. 2026-09-16 05:15 UTCEPSS rescore
  6. 2026-09-13 16:47 UTCEPSS rescore
  7. 2026-09-12 15:01 UTCEPSS rescore
  8. 2026-09-11 14:53 UTCEPSS rescore
  9. 2026-09-11 09:37 UTCEPSS rescore
  10. 2026-09-10 09:34 UTCEPSS rescore
  11. 2026-09-08 22:00 UTCEPSS rescore
  12. 2026-09-07 16:01 UTCEPSS rescore
  13. 2026-09-06 13:47 UTCEPSS rescore
  14. 2026-09-04 05:06 UTCEPSS rescore
  15. 2026-09-02 14:12 UTCEPSS rescore
  16. 2026-09-01 13:54 UTCEPSS rescore
  17. 2026-08-30 19:17 UTCEPSS rescore
  18. 2026-08-30 01:22 UTCEPSS rescore
  19. 2026-08-28 21:41 UTCEPSS rescore
  20. 2026-08-28 16:47 UTCVendor advisory
  21. 2026-08-28 16:00 UTCEG score recompute
  22. 2026-08-28 16:00 UTCVendor advisory
  23. 2026-08-27 14:25 UTCEPSS rescore
  24. 2026-08-26 14:46 UTCEPSS rescore
  25. 2026-08-25 13:49 UTCEPSS rescore
Show 75 more
  1. 2026-08-24 00:19 UTCVendor advisory
  2. 2026-08-23 17:54 UTCEG score recompute
  3. 2026-08-23 17:54 UTCVendor advisory
  4. 2026-08-23 00:19 UTCEPSS rescore
  5. 2026-08-21 23:49 UTCEPSS rescore
  6. 2026-08-20 22:55 UTCEPSS rescore
  7. 2026-08-20 21:29 UTCEG score recompute
  8. 2026-08-20 21:29 UTCVendor advisory
  9. 2026-08-19 17:03 UTCEPSS rescore
  10. 2026-08-18 13:48 UTCEPSS rescore
  11. 2026-08-17 13:47 UTCEPSS rescore
  12. 2026-08-17 10:41 UTCEG score recompute
  13. 2026-08-17 10:41 UTCVendor advisory
  14. 2026-08-16 14:56 UTCEPSS rescore
  15. 2026-08-16 12:57 UTCVendor advisory
  16. 2026-08-16 08:27 UTCVendor advisory
  17. 2026-08-16 04:05 UTCEG score recompute
  18. 2026-08-16 04:05 UTCVendor advisory
  19. 2026-08-16 02:14 UTCEPSS rescore
  20. 2026-08-15 01:30 UTCEPSS rescore
  21. 2026-08-15 00:25 UTCVendor advisory
  22. 2026-08-14 20:04 UTCVendor advisory
  23. 2026-08-14 15:42 UTCVendor advisory
  24. 2026-08-14 11:20 UTCVendor advisory
  25. 2026-08-14 06:55 UTCVendor advisory
  26. 2026-08-14 02:34 UTCEG score recompute
  27. 2026-08-14 02:34 UTCVendor advisory
  28. 2026-08-13 22:00 UTCEPSS rescore
  29. 2026-08-13 09:18 UTCVendor advisory
  30. 2026-08-13 04:57 UTCVendor advisory
  31. 2026-08-13 00:35 UTCVendor advisory
  32. 2026-08-12 20:14 UTCVendor advisory
  33. 2026-08-12 15:52 UTCEG score recompute
  34. 2026-08-12 15:52 UTCVendor advisory
  35. 2026-08-12 13:51 UTCEPSS rescore
  36. 2026-08-12 00:11 UTCVendor advisory
  37. 2026-08-11 19:50 UTCVendor advisory
  38. 2026-08-11 15:29 UTCEG score recompute
  39. 2026-08-11 15:29 UTCVendor advisory
  40. 2026-08-11 13:43 UTCEPSS rescore
  41. 2026-08-11 09:48 UTCVendor advisory
  42. 2026-08-11 05:19 UTCVendor advisory
  43. 2026-08-11 00:57 UTCEG score recompute
  44. 2026-08-11 00:57 UTCVendor advisory
  45. 2026-08-11 00:00 UTCEPSS rescore
  46. 2026-08-10 12:57 UTCVendor advisory
  47. 2026-08-10 08:35 UTCVendor advisory
  48. 2026-08-10 04:13 UTCVendor advisory
  49. 2026-08-09 23:52 UTCVendor advisory
  50. 2026-08-09 19:30 UTCVendor advisory
  51. 2026-08-09 15:09 UTCEG score recompute
  52. 2026-08-09 15:09 UTCVendor advisory
  53. 2026-08-09 13:46 UTCEPSS rescore
  54. 2026-08-09 10:47 UTCVendor advisory
  55. 2026-08-09 06:18 UTCVendor advisory
  56. 2026-08-09 01:56 UTCEG score recompute
  57. 2026-08-09 01:56 UTCVendor advisory
  58. 2026-08-08 16:37 UTCEPSS rescore
  59. 2026-08-08 13:41 UTCVendor advisory
  60. 2026-08-08 09:19 UTCVendor advisory
  61. 2026-08-08 04:58 UTCVendor advisory
  62. 2026-08-08 00:36 UTCVendor advisory
  63. 2026-08-07 20:14 UTCEG score recompute
  64. 2026-08-07 20:14 UTCVendor advisory
  65. 2026-08-07 15:52 UTCVendor advisory
  66. 2026-08-07 11:28 UTCVendor advisory
  67. 2026-08-07 07:07 UTCVendor advisory
  68. 2026-08-07 01:24 UTCVendor advisory
  69. 2026-08-06 19:43 UTCVendor advisory
  70. 2026-08-06 15:21 UTCEG score recompute
  71. 2026-08-06 15:21 UTCVendor advisory
  72. 2026-08-06 13:46 UTCEPSS rescore
  73. 2026-08-06 10:48 UTCVendor advisory
  74. 2026-08-06 06:25 UTCVendor advisory
  75. 2026-08-06 02:03 UTCVendor advisory

Related CVEs(same vendor + 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 August 28, 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 69.1% 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-42557

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