EUVD-2026-18390
GHSA-qv7j-4883-hwh7
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
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4Tags
Description
Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Sendfile#map_accel_path interpolates the value of the X-Accel-Mapping request header directly into a regular expression when rewriting file paths for X-Accel-Redirect. Because the header value is not escaped, an attacker who can supply X-Accel-Mapping to the backend can inject regex metacharacters and control the generated X-Accel-Redirect response header. In deployments using Rack::Sendfile with x-accel-redirect, this can allow an attacker to cause nginx to serve unintended files from configured internal locations. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.
Analysis
Rack::Sendfile in versions prior to 2.2.23, 3.1.21, and 3.2.6 allows remote attackers to inject regex metacharacters into X-Accel-Mapping request headers, enabling unescaped interpolation that manipulates the X-Accel-Redirect response header and causes nginx to serve unintended files from internal locations. No public exploit code or active exploitation has been confirmed; patch versions are available from the vendor.
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