CVE-2025-59152: 
Python vulnerability analysis and mitigation

CVE-2025-59152 affects Litestar, an Asynchronous Server Gateway Interface (ASGI) framework. The vulnerability was discovered in version 2.17.0 and disclosed on October 5, 2025. The issue allows attackers to completely bypass rate limits by manipulating the X-Forwarded-For header, rendering IP-based rate limiting ineffective (GitHub Advisory).

The vulnerability exists in Litestar's RateLimitMiddleware, which uses cachekeyfrom_request() to generate cache keys for rate limiting. When an X-Forwarded-For header is present, the middleware trusts it unconditionally and uses its value as part of the client identifier. Since clients can set arbitrary X-Forwarded-For values, each different spoofed IP creates a separate rate limit bucket. The vulnerability has been assigned a CVSS v3.1 base score of 5.3 (Moderate) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (GitHub Advisory).

The vulnerability has several significant impacts: it enables brute force protection bypass on authentication endpoints, making them vulnerable to credential stuffing attacks; allows API abuse by circumventing rate limiting protections; and enables resource exhaustion through unrestricted server requests. This is particularly problematic for applications deployed directly without a proxy during development or in containerized environments (GitHub Advisory).

The vulnerability has been patched in Litestar version 2.18.0. For immediate mitigation, applications can be deployed behind a properly configured reverse proxy that strips or overwrites client-controllable headers before they reach Litestar. The fix involves not trusting proxy headers unless explicitly configured and implementing proper validation of forwarded IP formats (GitHub Advisory).