CVE-2026-102831

JupyterLab: Cross-site scripting (XSS) in JupyterLab via notebook cells pasted from the system clipboard

HIGH
8.1
CVSS Score
Published: September 29, 2026 at 06:58 PM UTC
Updated: October 2, 2026 at 01:17 PM UTC
3 products affected across 1 vendorJupyterlabJupyterLite CoreNotebook

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Severity
HIGH8.1
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

JupyterLab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. From JupyterLab 4.5.0 until 4.5.11 and 4.6.4, from Notebook 7.5.0 until 7.6.3, and from JupyterLite Core 0.7.0 until 0.8.4, the system clipboard cell-paste path accepts attacker-controlled cell JSON without clearing metadata.trusted. When useSystemClipboardForCells is active and pasteCodeCellsWithoutOutput is disabled, a pasted code cell can mark HTML output as trusted, bypass output sanitization, and execute script in the authenticated JupyterLab origin without executing the cell. Markdown and raw cells are not affected because their output is sanitized. This issue is fixed in JupyterLab 4.5.11 and 4.6.4, Notebook 7.6.3, and JupyterLite Core 0.8.4.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 4.5.11v < 4.6.4
Affected range stops below 4.5.11, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.6.4, so it looks safe — our inference, not a vendor statement
v < 0.8.4
Affected range stops below 0.8.4, so it looks safe — our inference, not a vendor statement
v < 7.6.3
Affected range stops below 7.6.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.1HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-79CWE-345

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