CVE-2025-57816: 
Python vulnerability analysis and mitigation

Fides Webserver API's built-in IP-based rate limiting vulnerability (CVE-2025-57816) was discovered in versions prior to 2.69.1. The vulnerability affects the open-source privacy engineering platform's rate limiting functionality when deployed in environments with CDNs, proxies, or load balancers. The issue was disclosed on September 8, 2025, and was patched in version 2.69.1 (GitHub Advisory).

The vulnerability consists of two key technical issues: 1) The rate limiting system incorrectly uses the immediate connection source IP instead of the actual client IP, and 2) Rate limit counters are maintained in-memory per container rather than in a shared store. The vulnerability has been assigned a CVSS v4.0 base score of 6.3 (Medium) with the vector string CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N. The weakness is categorized as CWE-799: Improper Control of Interaction Frequency (GitHub Advisory).

The vulnerability impacts system availability in two ways: 1) Attackers can bypass rate limits, potentially leading to resource exhaustion, and 2) Attackers can cause denial of service for legitimate clients by deliberately triggering rate limits on infrastructure IPs. The vulnerability only affects deployments relying on Fides's built-in rate limiting for protection, while deployments using external rate limiting solutions such as WAFs or API gateways are not affected (GitHub Advisory).

The vulnerability has been patched in Fides version 2.69.1. Users are advised to upgrade to this version or later. For those unable to upgrade immediately, there are no application-level workarounds available. However, rate limiting can be implemented externally at the infrastructure level using a WAF, API Gateway, or similar technology (GitHub Advisory, GitHub Release).