9.6

CVE-2026-42557: jupyter jupyterlab Cross-site Scripting

CVSS: 9.6v3.1CriticalModified
AliasesGHSA-mqcg-5x36-vfcgBIT-jupyter-base-notebook-2026-42557BIT-jupyter-notebook-2026-42557
Published 13-05-2026Last modified 28-08-2026
Open JSON

Vulnerability summary

CVE-2026-42557 is a critical (CVSS 9.6) Cross-site Scripting vulnerability in jupyter jupyterlab. EPSS estimates a 0.71% chance of exploitation in the next 30 days, higher than 52.8% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.6/10
010
Critical · v3.1 (NVD)
EPSS score
0.71%
0%100%
Low · +0.34 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2 · Related 3
OPENSUSE-SU-2026:10748-1OPENSUSE-SU-2026:10749-1CGA-7WXR-FC9G-C6QC

Timeline

  1. 13-05-2026
    PublishedVulnerability first disclosed.
  2. 28-08-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

10 scores · 6 sources · 2 versions

EPSS trend

Probability

0.71%

Chance of exploitation in the next 30 days

Percentile

53%

Versus all other CVEs

30-day change

+0.34 pp

From 0.37% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.71%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Jupyter2 products
PyPI2 products
  • jupyterlab< 4.5.7
  • notebook≥ 7.0.0, < 7.5.6
Chainguard1 product
  • datahub-ingestion-fips< 1.5.0.1-r2
Debian1 product
  • jupyterlabAll versions (No fix recorded) | < 4.4.10+ds1+~3.1.0+~0.16.6+~cs1.4.4-3
Jupyterlab1 product
Ubuntu1 product
  • jupyterlabAll versions (No fix recorded)

6 vendors · 8 products

References

16 links
Show all 16 references