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No exploitation reportedFix available

CVE-2026-42557

No exploitation reported by the sources we read.

  • Published2026-05-13
  • Fixed in4.5.7
  • WeaknessCWE-79

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2026-05-1316:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-25 15:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-42557?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-42557?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Jupyter jupyterlab
BranchAffectedFixed in
4.5< 4.5.74.5.7
Jupyter notebook
BranchAffectedFixed in
7.x≥ 7.0.0, < 7.5.67.5.6

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • RHSA-2026:60520 Red Hat Product Security25 products fixed

    Red Hat Security Advisory: RHOAI 3.4.4 - Red Hat OpenShift AI

  • RHSA-2026:43038 Red Hat Product Security2 products fixed

    Red Hat Security Advisory: Migration Toolkit for Applications

Full record on NVD

Fix

  1. Update Jupyter jupyterlab to 4.5.7
  2. Vendor fix Red Hat Product Security RHSA-2026:60520 · 25 productsFor Red Hat OpenShift AI 3.4.4 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this errata update: https://docs.redhat.com/en/documentation/red_hat_openshift_ai/
  3. Vendor fix Red Hat Product Security RHSA-2026:43038 · 2 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied.
  4. Workaround from the vendor Red Hat Product Security RHSA-2026:60520 · 321 productsUsers should avoid opening or interacting with JupyterLab notebooks from untrusted sources. Exercise caution and verify the origin of any notebook before clicking buttons within its output, as this action could lead to the execution of arbitrary commands.

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CISA-ADPSSVC decisionnone2026-05-14
  • OpenCVESSVC decisionnone—
  • CNACVSS 4.08.6read 2026-10-23
  • CNACVSS 3.18.8read 2026-10-23
  • NVDCVSS 3.19.6read 2026-10-23
  • CNAweakness (CWE)CWE-79read 2026-10-23
  • FIRST EPSSEPSS score0.4 %2026-10-25
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
CVSS 4.0 vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published
2026-05-13
Last Modified
2026-08-28
NVD status
Modified

Frequently asked questions

What is CVE-2026-42557?

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.

Is CVE-2026-42557 actively exploited?

Active exploitation of CVE-2026-42557 has not been confirmed. Its EPSS score was 0.4% on 2026-10-25, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-42557?

CVE-2026-42557 has a CVSS v3 base score of 9.6 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.

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