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Vulnerabilities

Vulnerability · CVE-2026-67338

JupyterLab: Stored XSS in extension manager through package metadata unsanitized URI protocol

Published Jun 19, 2026 · catalog updated Oct 14, 2026 · JupyterLab: Stored XSS in

Check if you run it

No confirmed exploitation is on record for CVE-2026-67338. EPSS is 0.30%. Act only if a listed version of JupyterLab: Stored XSS in is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (JupyterLab: Stored XSS in).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Unknown—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.30%
Remediation
Advisory link
Affected products
PyPI jupyterlab

A malicious PyPI package can place a URL in its metadata. JupyterLab's Extension Manager renders this as the extension's home-page link without validating the protocol, so a user who clicks the extension name executes attacker-controlled JavaScript in the JupyterLab origin. ### Details One of the PyPI package's URL (jupyterlab/extensions/pypi.py) is copied straight into the rendered by the frontend in packages/extensionmanager/src/widget.tsx#L77-L88. ### Impact An attacker needs to publish a package to PyPI (no access to the target). When the package appears in a victim's extension manager list and the victim clicks the extension name, the payload runs in the JupyterLab origin. Preconditions: Extension Manager enabled with the default PyPI source, the malicious package appears in the victim's list/search results. ### Patches Patched in [4.5.9](https://github.com/jupyterlab/jupyterlab/releases/tag/v4.5.9), commits [4e61e07](https://github.com/jupyterlab/jupyterlab/commit/4e61e07d0a91145b53fbf96ac74b0387f6bc51f6) and [d5d961f](https://github.com/jupyterlab/jupyterlab/commit/d5d961f6e10a6442dddbf94d9a976b3897055a12)

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • PyPI jupyterlab0 → 4.5.9

How to fix CVE-2026-67338

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-67338. EPSS is 0.30%. Act only if a listed version of JupyterLab: Stored XSS in is installed.

Which versions are affected?

Compare what you have installed with 0 → 4.5.9. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-84. EPSS 0.30%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 19, 2026 · GitHub Advisory Database

    Detected

    A malicious PyPI package can place a URL in its metadata. JupyterLab's Extension Manager renders this as the extension's home-page link without validating the protocol, so a user who clicks the extension name executes attacker-controlled JavaScript in the JupyterLab origin. ### Details One of the PyPI package's URL (jupyterlab/extensions/pypi.py) is copied straight into the rendered by the fronten

  2. Oct 14, 2026 · GitHub Advisory Database

    Fix available

    jupyterlab fixed in 4.5.9

  3. Oct 14, 2026 · GitHub Advisory Database

    Fix available

    jupyterlab fixed in 4.5.9

  4. Oct 14, 2026 · GitHub Advisory Database

    Updated

    A malicious PyPI package can place a URL in its metadata. JupyterLab's Extension Manager renders this as the extension's home-page link without validating the protocol, so a user who clicks the extension name executes attacker-controlled JavaScript in the JupyterLab origin. ### Details One of the PyPI package's URL (jupyterlab/extensions/pypi.py) is copied straight into the rendered by the fronten

Sources

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.