Jupyter: JupyterLab: Cross-site scripting (XSS) via crafted settings file (`overrides.json`)
Jupyter
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- Severity
- High, CVSS 8.6
- CVSS vector
- CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:L
- Record
- CVE-2026-73417
- Affects
- Jupyter
- Known exploited
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Published
- Record first published by the source
- July 22, 2026
- Source last modified
- August 12, 2026
Description
JupyterLab 4.5+ allows notebook settings to be shared and applied through an overrides.json file using the Import button in the Settings Editor.
Certain notebook display settings were not properly validated before being applied. As a result, a crafted settings file could contain hidden instructions that run as code inside JupyterLab when imported, instead of only changing a display preference.
Because importing a settings file appears harmless, a user could import a file shared by another party without realizing it could do more. On multi-tenant file systems without proper permission control, another user could plant a malicious overrides.json.
> CVE assignment pending, GitHub CNA is experiencing severe backlog
Impact
When a malicious settings file is applied, the embedded code runs with the same access as the affected user. This could allow an attacker to read or modify that user's notebooks and files, and to run code on the user's behalf through the notebook server, including on any connected kernel.
User Interaction vs Privileges Required
Write access to a loaded settings location
If an attacker can write to a directory JupyterLab loads settings from (e.g. on shared or multi-tenant file system), they could place a crafted overrides.json that is applied to another user automatically at startup. This requires high privilages but no action by the victim.
User-imported settings file
A user can import a crafted overrides.json through the Import button in the Settings Editor, having received it from another party. This requires no privileges but a deliberate action by the victim, who reasonably expects a settings file to change preferences rather than run code.
Patches
JupyterLab 4.6.2 and 4.5.10 were patched.
Workarounds
None
Hardening
1. Treat a settings file as something that can affect how JupyterLab behaves, not only how it appears. Administrators are encouraged to establish a trusted process for distributing configuration rather than relying on ad-hoc importing of shared files.
2. On multi-tenant or shared file systems, restrict write permissions on the application settings directory and other Jupyter configuration paths so that one user cannot place an overrides.json (or other configuration) readable by another user. A settings file in these locations is applied automatically, without an import step, so directory permissions are the primary control against cross-user tampering.
Description quoted from the NVD record.
Who is affected
Jupyter (also called JupyterLab) is a tool where people write and run code, notes and charts in documents called notebooks. This flaw affects JupyterLab 4.5 and later releases that do not include the fixes in 4.5.10 or 4.6.2. Certain display settings are not checked, so a crafted settings file can run hidden code when someone imports it through the Settings Editor. On shared systems without proper permission controls, another user could plant such a file that loads automatically at startup. The code runs with the user's access and could read or change their notebooks and files and run code on their behalf. This flaw is rated High.
What to do
- The person who installed or runs JupyterLab for your organization, or the IT provider who manages it, should handle this.
- Update JupyterLab to
4.5.10or4.6.2, which fix this flaw. No workaround is named for this flaw. - If an IT provider or vendor runs JupyterLab for you, send them this advisory and ask when the update will be done.
- Only apply settings files that come through a trusted process set up by whoever runs JupyterLab, not files shared casually by others.
- On shared systems used by several people, restrict who can write to the folders where JupyterLab loads its settings, so one user cannot place a settings file that another user will load.
Analysis written from the source record as of August 12, 2026 and reviewed before publishing.