Cross-site scripting in Jupyter Notebook - CVE-2026-40171
Published: May 4, 2026
Vulnerability identifier: #VU129538
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-40171
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Jupyter
Affected software:
Jupyter Notebook
Jupyter Notebook
Detailed vulnerability description
The vulnerability allows a remote user to steal authentication tokens and execute arbitrary code.
The vulnerability exists due to cross-site scripting in the help extension command linker functionality when rendering malicious notebook content. A remote privileged user can craft a malicious notebook file and induce a single click on attacker-controlled elements to steal authentication tokens and execute arbitrary code.
User interaction is required to open a malicious notebook file and click an element made to appear indistinguishable from a legitimate control.
How to mitigate CVE-2026-40171
Install security update from vendor's website.