JupyterLab XSS in image viewer leading to RCE

Executive brief

JupyterLab is a popular web-based interactive development environment for notebooks, code, and data. A vulnerability in its image viewing component allows an attacker to execute malicious code on the server if a user opens a specially crafted image file and then views it in a new browser tab. This could lead to full system compromise, unauthorized data access, or disruption of research operations.

Technical details

A Cross-Site Scripting (XSS) vulnerability exists in the JupyterLab image viewer extension (@jupyterlab/imageviewer-extension:plugin). The flaw is triggered when a user opens a malicious image file within the viewer and subsequently opens that image in a new browser tab. Because the XSS executes within the context of the JupyterLab session, it can be leveraged to achieve Remote Code Execution (RCE) on the underlying server. The attack requires user interaction (opening the file) and has high complexity due to the specific sequence of actions required. Patches are available in versions 4.6.2 and 4.5.10.

Affected products

• Jupyter jupyterlab >= 4.6.0, <= 4.6.1; <= 4.5.9

Timeline

• 2026-07-21: disclosed
• 2026-07-22: advisory
• 2026-07-22: patched

References

• https://api.github.com/users/krassowski
• https://github.com/krassowski
• https://api.github.com/users/krassowski/gists%7B/gist_id%7D
• https://api.github.com/users/krassowski/repos
• https://avatars.githubusercontent.com/u/5832902?v=4
• https://api.github.com/users/krassowski/events%7B/privacy%7D