CVE-2025-27111 is a vulnerability in the Rack middleware component Rack::Sendfile that allows an attacker to inject escape sequences, such as newline characters, into the X-Sendfile-Type header. This leads to log injection, which can distort log files and hinder security auditing and incident investigation. The issue affects multiple Rack versions prior to 2.2.12, and versions 3.0 up to but not including 3.0.13, as well as 3.1 up to but not including 3.1.11. The vulnerability has a medium severity rating with a CVSS score of 6.9. A fix is available in Rack versions 2.2.12, 3.0.13, and 3.1.11. Mitigation involves updating to these fixed versions or removing the use of Rack::Sendfile.