Scancode.io Reflected Cross-Site Scripting (XSS) in license endpoint

Summary

In the /license/ endpoint, the detailed view key is not properly validated and sanitized, which can result in a potential cross-site scripting (XSS) vulnerability when attempting to access a detailed license view that does not exist.

Details

In the /license/ endpoint, the license_details_view function is vulnerable to a potential cross-site scripting (XSS) attack due to inadequate validation and sanitization of the key parameter. This vulnerability arises when attempting to access a key with malicious javascript.

def license_details_view(request, key):
    """
    Display all available information about a given license `key` followed by
    the full license text.
    """
    licenses = get_licenses()
    try:
        data = saneyaml.dump(licenses[key].to_dict())
        text = licenses[key].text
    except KeyError:
        return HttpResponseNotFound(f"License {key} not found.") # Leads to cross-site scripting when key is malicious javascript
    return HttpResponse(f"<pre>{data}</pre><hr><pre>{text}</pre>")

PoC

1. Access following endpoint on scancode.io instance: http://localhost/license/%3Cscript%3Ealert(document.cookie);%3C/script%3E/

Impact

Attackers can exploit the vulnerability to inject malicious scripts into the response generated by the license_details_view function. When unsuspecting users visit the page, their browsers will execute the injected scripts, leading to unauthorized actions, session hijacking, or stealing sensitive information.