Bug 2515249 (CVE-2026-73626)

Summary: CVE-2026-73626 jupyterlab: JupyterLab: Extension allowlist bypass allows unauthorized installations
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: rjohnson
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in JupyterLab where a missing 'await' in the `PyPIExtensionManager.install()` function could lead to an allowlist/blocklist enforcement gap. This vulnerability allows direct callers of `install()` to bypass security checks, potentially enabling the installation of unauthorized extensions. This issue affects deployments where a custom extension or downstream integration calls `install()` directly with untrusted input, an allowlist/blocklist is configured, and the PyPI Extension Manager is enabled.
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Description OSIDB Bzimport 2026-08-13 11:53:51 UTC 
JupyterLab versions >=4.6.0,<=4.6.1 and <=4.5.9 contain an allowlist/blocklist enforcement gap in PyPIExtensionManager.install(). A missing 'await' caused the is_install_allowed coroutine to never execute, so the extension allowlist/blocklist check was not enforced for direct callers of install(). The stock JupyterLab HTTP API and Extension Manager UI are not affected, as they perform a separate, correctly awaited check. The issue affects only deployments where a custom extension or downstream integration imports PyPIExtensionManager and calls install() directly with a package name influenced by untrusted input, an allowlist/blocklist is configured, the PyPI Extension Manager is enabled, and kernels and terminals are disabled or delegated to remote hosts. Fixed in JupyterLab 4.6.2 and 4.5.10.