---
id: CVE-2025-25296
aliases:
  - GHSA-wpq5-3366-mqw4
  - PYSEC-2026-1504
title: >-
  Label Studio allows Cross-Site Scripting (XSS) via GET request to
  `/projects/upload-example` endpoint
summary: >-
  Label Studio allows Cross-Site Scripting (XSS) via GET request to
  `/projects/upload-example` endpoint
severity: medium
cvss: 6.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'
vendor: label-studio
product: label-studio
ecosystem: pip
affected:
  - label-studio < 1.16.0
patched:
  - label-studio 1.16.0
published: '2025-02-14'
updated: '2026-07-07'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-wpq5-3366-mqw4'
references:
  - url: >-
      https://github.com/HumanSignal/label-studio/security/advisories/GHSA-wpq5-3366-mqw4
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-25296'
  - url: >-
      https://github.com/HumanSignal/label-studio/commit/8cf6958e1e27ef6a03ed287e674470975d340885
  - url: 'https://github.com/HumanSignal/label-studio'
tags:
  - osv
  - pip
  - exploit-available
epss: 0.01898
epssPercentile: 0.7877
ingestedAt: '2026-07-08T18:25:53.868Z'
exploits:
  github: 1
  githubRepos:
    - 'https://github.com/math-x-io/CVE-2025-25296'
  nuclei:
    - CVE-2025-25296
  checkedAt: '2026-09-24T07:52:53.151Z'
exploitAvailable: true
---

## Overview

## Description
Label Studio's `/projects/upload-example` endpoint allows injection of arbitrary HTML through a `GET` request with an appropriately crafted `label_config` query parameter. By crafting a specially formatted XML label config with inline task data containing malicious HTML/JavaScript, an attacker can achieve Cross-Site Scripting (XSS). While the application has a Content Security Policy (CSP), it is only set in report-only mode, making it ineffective at preventing script execution.

The vulnerability exists because the upload-example endpoint renders user-provided HTML content without proper sanitization on a GET request. This allows attackers to inject and execute arbitrary JavaScript in victims' browsers by getting them to visit a maliciously crafted URL.

This is considered vulnerable because it enables attackers to execute JavaScript in victims' contexts, potentially allowing theft of sensitive data, session hijacking, or other malicious actions.

## Steps to reproduce
1. Create a malicious label config that includes an XSS payload in embedded task data:

```xml
<View><!-- {"data": {"text": "<div><img src=x
onerror=eval(atob(`YWxlcnQoIlhTUyIp`))></div>"}} --><HyperText name="text"
value="$text"/></View>
```


2. URL encode the payload and access the following URL:

- http://app/projects/upload-example/?label_config=%3CView%3E%3C!--%20{%22data%22:%20{%22text%22:%20%22%3Cdiv%3E%3Cimg%20src=x%20onerror=eval(atob(`YWxlcnQoIlhTUyIp`))%3E%3C/div%3E%22}}%20--%3E%3CHyperText%20name=%22text%22%20value=%22$text%22/%3E%3C/View%3E

When executed, the payload causes the application to render an HTML page containing an img tag that fails to load, triggering the onerror event handler which executes base64-decoded JavaScript, demonstrating successful XSS execution in the victim's browser.
   
## Mitigations
- Enable the Content Security Policy in enforcement mode instead of report-only mode to actively block unauthorized script execution
- Deprecate the `GET` behavior at the `example-config` endpoint since it's not used 

## Impact
The vulnerability requires no special privileges and can be exploited by getting a victim to visit a crafted URL. The impact is high as it allows arbitrary JavaScript execution in victims' browsers, potentially exposing sensitive data or enabling account takeover through session theft.

## Affected packages

- `label-studio < 1.16.0`

## Remediation

Upgrade to a patched release:

- `label-studio 1.16.0`