CVE-2026-42557

Medium

Elevated severity or exploit probability.

CVSS base

9.6 CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

EPSS — probability of exploitation (30 days)

0.4%

30.8th percentile

CISA KEV

Not listed

Weakness / dates

CWE-79

Published 2026-05-13 · modified 2026-08-28

CVSS breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Attack Vector	N	Network
Attack Complexity	L	Low
Privileges Required	N	None
User Interaction	R	Required
Scope	C	Changed
Confidentiality	H	High
Integrity	H	High
Availability	H	High

Timeline

2026-05-13 — Published (NVD)
2026-08-28 — Last modified (NVD)

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.

Affected

jupyter

References

Official: NVD · CVE.org