PYSEC-2026-1334

SERVER_SIDE_FIDES_API_URL is a server-side configuration environment variable used by the Fides Privacy Center to communicate with the Fides webserver backend. The value of this variable is a URL which typically includes a private IP address, private domain name, and/or port.

This vulnerability allows an unauthenticated attacker to make a HTTP GET request from the Privacy Center that discloses the value of this server-side URL.

Impact

Disclosure of server-side configuration giving an attacker information on server-side ports, private IP addresses, and/or private domain names.

Patches

The vulnerability has been patched in Fides version 2.39.2. Users are advised to upgrade to this version or later to secure their systems against this threat.

Workarounds

There are no workarounds.

Proof of Concept

1. Set the value of the environment variable FIDES_PRIVACY_CENTER__SERVER_SIDE_FIDES_API_URL of your Fides Privacy Center container before start-up to a private value such as https://some.private.domain.name/api/v1 and start the Privacy Center application.

2. Once the application is up, perform a HTTP GET request of the Privacy Center's main page e.g. https://privacy.example.com . The value of SERVER_SIDE_FIDES_API_URL is returned in the response's body.

~ ❯ curl -s https://privacy.example.com/ | \
grep '__NEXT_DATA__' | \
sed 's/.*<script id="__NEXT_DATA__" type="application\/json">//;s/<\/script>.*//' | \
jq '.props.serverEnvironment.settings.SERVER_SIDE_FIDES_API_URL'
"https://some.private.domain.name/api/v1"