CVE-2025-61780 Vulnerability Summary Vulnerability Overview Vulnerability Name: Rack::Sendfile Information Disclosure and Access Control Bypass Vulnerability ID: CVE-2025-61780 CVSS Score: 3.3 (Medium) Description: In the Ruby Web server interface Rack, an information disclosure vulnerability exists when running behind a proxy that supports the header (such as Nginx). Attackers can deceive the proxy into sending a redirect response by crafting specific and headers, thereby bypassing the access controls enforced by the proxy to access internal endpoints (such as admin pages) or read sensitive files. Affected Scope Affected Software: Rack Affected Versions: Versions prior to 2.2.20, 3.1.18, and 3.2.3. Trigger Conditions: 1. The application uses a proxy that supports (e.g., Nginx). 2. The proxy does not set or strip the and headers. 3. The application exposes an endpoint that returns a response. Remediation 1. Upgrade Software: Upgrade Rack to version 2.2.20, 3.1.18, or 3.2.3. 2. Configure Proxy: Configure the proxy to always set or strip the header. 3. Application Configuration: Disable sendfile in Rails applications. References GitHub Commit 1 GitHub Commit 2 GitHub Commit 3 GitHub Advisory