CVE-2026-34830
Rack::Sendfile header-based X-Accel-Mapping regex injection enables unauthorized X-Accel-Redirect
Impact
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 packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| rubygems | rack | < 2.2.23 | 2.2.23 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Rack | Rack | before 2.2.23 from 3.0.0 before 3.1.21 from 3.2.0 before 3.2.6 |