Medium severity · published Aug 1, 2026
CVE-2026-67338
JupyterLab before 4.5.9 Stored XSS via Extension Manager
6.1
CVSS
0.3%
EPSS
No
On KEV
Description
JupyterLab before 4.5.9 contains a stored cross-site scripting vulnerability in the Extension Manager that fails to validate URI protocols in package metadata URLs. Attackers can publish malicious PyPI packages with javascript: URLs in project metadata that execute arbitrary JavaScript in the JupyterLab origin when users click the extension name.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 23% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
JU
jupyterlab · jupyterlab
before 4.5.9 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-67338
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-67338
vendor-advisory
https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-vmhf-c436-hxj4
patch
https://github.com/jupyterlab/jupyterlab/commit/4e61e07d0a91145b53fbf96ac74b0387f6bc51f6
patch
https://github.com/jupyterlab/jupyterlab/commit/d5d961f6e10a6442dddbf94d9a976b3897055a12
third-party-advisory
https://www.vulncheck.com/advisories/jupyterlab-before-stored-xss-via-extension-manager
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