🛡️ CVE-2024-35225 — jupyter-server-proxy

🔴 CVSS 9.5 — Critical ✅ No Known Exploit CWE-116 OSV
9.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Jupyter Server Proxy has a reflected XSS issue in host parameter

Impact

There is a reflected cross-site scripting (XSS) issue in jupyter-server-proxy[1]. The /proxy endpoint accepts a host path segment in the format /proxy/<host>. When this endpoint is called with an invalid host value, jupyter-server-proxy replies with a response that includes the value of host, without sanitization [2]. A third-party actor can leverage this by sending a phishing link with an invalid host value containing custom JavaScript to a user. When the user clicks this phishing link, the browser renders the response of GET /proxy/<host>, which runs the custom JavaScript contained in host set by the actor.

As any arbitrary JavaScript can be run after the user clicks on a phishing link, this issue permits extensive access to the user's JupyterLab instance for an actor. This issue exists in the latest release of jupyter-server-proxy, currently v4.1.2.

Impacted versions: >=3.0.0,<=4.1.2

Patches

The patches are included in ==4.2.0 and ==3.2.4.

Workarounds

Server operators who are unable to upgrade can disable the jupyter-server-proxy extension with:

```

jupyter server extension disable jupyter-server-proxy

```

References

[1] : https://github.com/jupyterhub/jupyter-server-proxy/

[2] : https://github.com/jupyterhub/jupyter-server-proxy/blob/62a290f08750f7ae55a0c29ca339c9a39a7b2a7b/jupyter_server_proxy/handlers.py#L328

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality high, integrity high, availability high.

Weakness class

CVE-2024-35225 is classified as CWE-116: Improper Encoding or Escaping of Output. Output is emitted without encoding it for the context it lands in, so data is interpreted as markup or code.

Affected software

CVE-2024-35225 is recorded against 1 package.

  • jupyter-server-proxy (from 4.0.0 up to 4.2.0)

Timeline and source

Published on 11 June 2024 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from OSV.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
github.com (Package)
github.com (Web)
github.com (Web)

Details

Severity CRITICAL
CVSS Score 9.5
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
CWE CWE-116
Public Exploit ✅ No
Source OSV
Published 2024-06-11
Updated 2026-08-12
Modified 2026-06-17

Affected Packages

Software From version Fixed in
jupyter-server-proxy 4.0.0 4.2.0

Similar Threats

Exploit Protection

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