Rack has Content-Length mismatch in Rack::Files error responses

Summary Rack::Filesfail sets the Content-Length response header using Stringsize instead of Stringbytesize. When the response body contains multibyte UTF-8 characters, the declared Content-Length is smaller than the number of bytes actually sent on the wire. Because Rack::Files reflects the...

GHSA-QV7J-4883-HWH7 Rack::Sendfile header-based X-Accel-Mapping regex injection enables unauthorized X-Accel-Redirect

Summary Rack::Sendfilemapaccelpath 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...

Rack::Sendfile header-based X-Accel-Mapping regex injection enables unauthorized X-Accel-Redirect

Summary Rack::Sendfilemapaccelpath 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...

EUVD-2026-18390

Rack::Sendfile header-based X-Accel-Mapping regex injection enables unauthorized X-Accel-Redirect...

EUVD-2026-18388

Rack's multipart parsing without Content-Length header allows unbounded chunked file uploads...

GHSA-8VQR-QJWX-82MW Rack's multipart parsing without Content-Length header allows unbounded chunked file uploads

Summary Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENTLENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size...

EUVD-2026-18380

Rack has a root directory disclosure via unescaped regex interpolation in Rack::Directory...

GHSA-7MQQ-6CF9-V2QP Rack has a root directory disclosure via unescaped regex interpolation in Rack::Directory

Summary Rack::Directory interpolates the configured root path directly into a regular expression when deriving the displayed directory path. If root contains regex metacharacters such as +, , or ., the prefix stripping can fail and the generated directory listing may expose the full filesystem pa...

Rack has a root directory disclosure via unescaped regex interpolation in Rack::Directory

Summary Rack::Directory interpolates the configured root path directly into a regular expression when deriving the displayed directory path. If root contains regex metacharacters such as +, , or ., the prefix stripping can fail and the generated directory listing may expose the full filesystem pa...

Rack has quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encoding header

Summary Rack::Utils.selectbestencoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard entries. Because this method is used by Rack::Deflater to choose a response encoding, an unauthenticated attacker can send a single request with a crafted...

EUVD-2026-18378

Rack has quadratic complexity in Rack::Utils.selectbestencoding via wildcard Accept-Encoding header...

GHSA-V569-HP3G-36WR Rack has quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encoding header

Summary Rack::Utils.selectbestencoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard entries. Because this method is used by Rack::Deflater to choose a response encoding, an unauthenticated attacker can send a single request with a crafted...

EUVD-2026-18423

Rack: Forwarded Header semicolon injection enables Host and Scheme spoofing...

Rack: Forwarded Header semicolon injection enables Host and Scheme spoofing

Summary Rack::Utils.forwardedvalues parses the RFC 7239 Forwarded header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header such as: http Forwarded: for="127.0.0.1;host=evil.com;proto=https" can be interpreted by Rack as...

GHSA-RX22-G9MX-QRHV Rack's improper unfolding of folded multipart headers preserves CRLF in parsed parameter values

Summary Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result,...

EUVD-2026-18417

Rack's improper unfolding of folded multipart headers preserves CRLF in parsed parameter values...

EUVD-2026-18368

Rack's greedy multipart boundary parsing can cause parser differentials and WAF bypass...

Rack's greedy multipart boundary parsing can cause parser differentials and WAF bypass.

Summary Rack::Multipart::Parser extracts the boundary parameter from multipart/form-data using a greedy regular expression. When a Content-Type header contains multiple boundary parameters, Rack selects the last one rather than the first. In deployments where an upstream proxy, WAF, or intermedia...

GHSA-VGPV-F759-9WX3 Rack's greedy multipart boundary parsing can cause parser differentials and WAF bypass.

Summary Rack::Multipart::Parser extracts the boundary parameter from multipart/form-data using a greedy regular expression. When a Content-Type header contains multiple boundary parameters, Rack selects the last one rather than the first. In deployments where an upstream proxy, WAF, or intermedia...

Interpretation Conflict

Overview rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between the so-called middleware into a singl...