AI Threat Alert

CVE-2026-67338

MEDIUM
Published August 1, 2026

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...

Full CISO analysis pending enrichment.

How severe is it?

CVSS 3.1
6.1 / 10
EPSS
N/A
Exploitation Status
No known exploitation
Sophistication
N/A

What is the attack surface?

AV AC PR UI S C I A
AV Network
AC Low
PR None
UI Required
S Changed
C Low
I Low
A None

What should I do?

No patch available

Monitor for updates. Consider compensating controls or temporary mitigations.

Which compliance frameworks are affected?

Compliance analysis pending. Sign in for full compliance mapping when available.

Frequently Asked Questions

What is CVE-2026-67338?

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.

Is CVE-2026-67338 actively exploited?

No confirmed active exploitation of CVE-2026-67338 has been reported, but organizations should still patch proactively.

How to fix CVE-2026-67338?

No patch is currently available. Monitor vendor advisories for updates.

What is the CVSS score for CVE-2026-67338?

CVE-2026-67338 has a CVSS v3.1 base score of 6.1 (MEDIUM).

What are the technical details?

Original Advisory

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.

Weaknesses (CWE)

CWE-84 Improper Neutralization of Encoded URI Schemes in a Web Page Primary

CWE-84 — Improper Neutralization of Encoded URI Schemes in a Web Page: The web application improperly neutralizes user-controlled input for executable script disguised with URI encodings.

  • [Implementation] Resolve all URIs to absolute or canonical representations before processing.
  • [Implementation] Carefully check each input parameter against a rigorous positive specification (allowlist) defining the specific characters and format allowed. All input should be neutralized, not just parameters that the user is supposed to specify, but all data in the request, including tag attributes, hidden fields, cookies, headers, the URL itself, and so forth. A common mistake that leads to continuing XSS vulnerabilities is to validate only fields that are expected to be redisplayed by the site. We often encounter data from the request that is reflected by the application server or the application that the development team did not anticipate. Also, a field that is not currently reflected may be used by a future developer. Therefore, validating ALL parts of the HTTP request is recommended.

Source: MITRE CWE corpus.

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

References

Timeline

Published
August 1, 2026
Last Modified
August 1, 2026
First Seen
August 1, 2026
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