CVE-2025-57816 is a medium-severity vulnerability affecting ethyca's open-source privacy engineering platform, Fides, specifically versions prior to 2.69.1. The vulnerability arises from improper control of interaction frequency (CWE-799) due to ineffective IP-based rate limiting in the Fides Webserver API. The root cause is that the built-in rate limiting mechanism incorrectly applies limits based on the IP addresses of directly connected infrastructure components such as CDNs, proxies, or load balancers, rather than the actual client IP addresses. Additionally, the rate limiting counters are stored in-memory on individual servers rather than in a shared store, which further undermines the effectiveness of rate limiting in distributed environments. As a result, attackers can bypass the intended rate limits by exploiting the infrastructure setup, enabling them to flood the API with excessive requests. This can lead to denial of service (DoS) conditions, degrading the availability of the Fides platform. The vulnerability does not require authentication or user interaction, and the attack vector is network-based. Deployments that rely solely on Fides's built-in rate limiting are vulnerable, whereas those using external rate limiting solutions such as Web Application Firewalls (WAFs), API gateways, or similar infrastructure-level protections are not affected. The issue was addressed in version 2.69.1 of Fides by correcting the rate limiting logic. No application-level workarounds exist, so upgrading or implementing external rate limiting is necessary to mitigate the risk. There are no known exploits in the wild at this time.

For European organizations using Fides versions prior to 2.69.1 with default built-in rate limiting, this vulnerability poses a risk of denial of service attacks that can disrupt privacy engineering operations. Since Fides is used to manage privacy compliance and data governance, unavailability could delay or impair compliance efforts with regulations such as GDPR, potentially leading to regulatory scrutiny or operational setbacks. The vulnerability does not directly expose sensitive data or allow privilege escalation, so confidentiality and integrity impacts are low. However, the availability impact can be significant if attackers exploit the bypass to overwhelm the API. Organizations relying on cloud or hybrid infrastructure with CDNs, proxies, or load balancers are particularly at risk due to the flawed IP-based rate limiting logic. The lack of authentication and user interaction requirements lowers the barrier for exploitation, increasing the threat surface. However, the scope is limited to deployments using the vulnerable Fides versions without external rate limiting controls, which may reduce the overall impact. European organizations with critical privacy engineering workflows dependent on Fides should prioritize remediation to maintain operational continuity and compliance posture.

1. Upgrade all Fides deployments to version 2.69.1 or later, where the rate limiting issue is fixed. 2. If immediate upgrade is not feasible, implement external rate limiting at the infrastructure level using Web Application Firewalls (WAFs), API gateways, or load balancers that support client IP-based rate limiting. Ensure these solutions correctly identify and use the original client IP, for example, by parsing the X-Forwarded-For header or equivalent. 3. Avoid relying solely on Fides's built-in rate limiting in environments with CDNs, proxies, or load balancers. 4. Monitor API traffic patterns for unusual spikes or anomalies that may indicate attempted DoS attacks. 5. Review and adjust infrastructure configurations to ensure that client IP addresses are preserved and correctly forwarded to backend services. 6. Conduct regular security assessments and penetration tests focusing on rate limiting and DoS resilience. 7. Document and communicate the upgrade and mitigation plan to relevant teams to ensure timely action.