Skip to content
CVE PROGRAM SOURCE RECORD5.9 Medium

CVE-2026-34830

Rack: Rack::Sendfile regex injection via HTTP_X_ACCEL_MAPPING header allows arbitrary file reads through nginx

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

rack rack

  • < 2.2.23affected
  • >= 3.0.0.beta1, < 3.1.21affected
  • >= 3.2.0, < 3.2.6affected

References