GHSA-c336-7962-wfj2 — medium GitHub Advisory (CVE-2026-23528) in pip/distributed

Description

Impact

When Jupyter Lab, jupyter-server-proxy and Dask distributed are all run together it is possible to craft a URL which will result in code being executed by Jupyter due to a cross-side-scripting (XSS) bug in the Dask dashboard.

It is possible for attackers to craft a phishing URL that assumes Jupyter Lab and Dask may be running on localhost and using default ports. If a user clicks on the malicious link it will open an error page in the Dask Dashboard via the Jupyter Lab proxy which will cause code to be executed by the default Jupyter Python kernel.

In order for a user to be impacted they must be running Jupyter Lab locally on the default port (with the jupyter-server-proxy) and a Dask distributed cluster on the default port. Then they would need to click the link which would execute the malicious code.

Patches

This has been fixed in the 2026.1.0 release. All users should upgrade to this version.

Mitigations

There are no known workarounds for this bug. The only complete solution is to upgrade to a newer release of Dask. However, there are a few things you could do to reduce your risk.

It is possible to avoid code execution via Jupyter by uninstalling the jupyter-server-proxy and accessing the Dask dashboard directly at it's URL. However, it is still possible for an attacker to craft a URL that executes JavaScript in the user's browser in the Dask dashboard. Which is still a moderate vulnerability. Therefore we recommend all users upgrade to the latest Dask release.

Another potential mitigation is to ensure both Jupyter and the Dask dashboard are running on non-standard ports. While this doesn't resolve the problem it reduces the chance of this being exploited. If an attacker knew which ports you were using they could still craft a malicious URL, but it would require a more targeted attack.

Basic information

Type: reviewed
Severity: medium
Advisory on GitHub: Open advisory ↗
Repository advisory: Open repository advisory ↗
Source code: Browse source ↗
Published (advisory): 2026-01-16 16:58:16 UTC
Updated: 2026-06-09 10:34:52 UTC
GitHub reviewed: 2026-01-16 16:58:16 UTC
NVD published: 2026-01-16

Score	Percentile
0.02%	3.78%

CVSS Scores

Base score	Version	Severity	Vector
5.3	4.0	—	`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network. Attack complexity (AC:L) Exploitation conditions are straightforward and stable. Attack requirements (AT:N) No additional preconditions are required beyond normal reachability. Privileges required (PR:N) No privileges are required. User interaction (UI:P) A user has to participate (for example click/open/approve). Vulnerable system confidentiality impact (VC:L) Limited confidentiality impact on the vulnerable system. Vulnerable system integrity impact (VI:L) Limited integrity impact on the vulnerable system. Vulnerable system availability impact (VA:N) No availability impact on the vulnerable system. Subsequent system confidentiality impact (SC:N) No confidentiality impact on subsequent systems. Subsequent system integrity impact (SI:N) No integrity impact on subsequent systems. Subsequent system availability impact (SA:N) No availability impact on subsequent systems.

Identifiers

Type	Value
GHSA	GHSA-c336-7962-wfj2 ↗
CVE	CVE-2026-23528 ↗

CWEs

CWE id	Name
CWE-79	Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-250	Execution with Unnecessary Privileges

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem	Package	Vulnerable range	First patched	Vulnerable functions
pip	distributed	< 2026.1.0	2026.1.0	—

Dask Distributed is Vulnerable to Remote Code Execution via Jupyter Proxy and Dashboard