CVE-2025-53528: Zmievsa Cadwyn

High severity, CVSS 7.6. EPSS: 0.2% chance of exploitation in the next 30 days.

Cadwyn creates production-ready community-driven modern Stripe-like API versioning in FastAPI. In versions before 5.4.3, the version parameter of the "/docs" endpoint is vulnerable to a Reflected XSS (Cross-Site Scripting) attack. This XSS would notably allow an attacker to execute JavaScript code on a user's session for any application based on Cadwyn via a one-click attack. The vulnerability has been fixed in version 5.4.3.

Affected products

• Zmievsa Cadwyn: before 5.4.3 (fixed in 5.4.3)

Published 2025-07-21. Last modified 2026-06-17.