CVE-2026-34830

A flaw was found in Rack. A remote attacker can exploit this vulnerability by injecting regular expression metacharacters into the X-Accel-Mapping request header. This improper input validation in Rack::Sendfile#map_accel_path allows the attacker to control the generated X-Accel-Redirect response header. Consequently, in deployments using Rack::Sendfile with x-accel-redirect, this can cause nginx to serve unintended files from configured internal locations, leading to information disclosure.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.