CVE-2025-25296 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in label-studio. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for label-studio — see the affected versions and patch details below.
Label Studio allows Cross-Site Scripting (XSS) via GET request to `/projects/upload-example` endpoint
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-25296.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
label-studioReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
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
- Create a malicious label config that includes an XSS payload in embedded task data:
<View><!-- {"data": {"text": "<div><img src=x
onerror=eval(atob(`YWxlcnQoIlhTUyIp`))></div>"}} --><HyperText name="text"
value="$text"/></View>
- URL encode the payload and access the following URL:
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
GETbehavior at theexample-configendpoint 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
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | label-studio | all versions | 1.16.0pip install --upgrade 'label-studio==1.16.0' |
Affected Products
label studiohumansignalResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for label-studio, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update label-studio to 1.16.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-25296 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
How to detect CVE-2025-25296
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2025-25296 -u https://target- Template
- Label Studio < 1.16.0 - Cross-Site Scripting
- Severity
- medium
- Impact
- Attackers can execute arbitrary JavaScript in victims' browsers, potentially leading to data theft, session hijacking, or other malicious actions.
- Remediation
- Update to version 1.16.0 or later to patch the vulnerability.
Template by ProjectDiscovery nuclei-templates (0x_Akoko), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2025-25296 in your dependencies?
Find it across PyPI, including transitive dependencies.