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...

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...

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's multipart byte range processing allows denial of service via excessive overlapping ranges

Summary Rack::Utils.getbyteranges parses the HTTP Range header without limiting the number of individual byte ranges. Although the existing fix for CVE-2024-26141 rejects ranges whose total byte coverage exceeds the file size, it does not restrict the count of ranges. An attacker can supply many...

PT-2026-29913

Summary Rack::Request parses the Host header using an AUTHORITY regular expression that accepts characters not permitted in RFC-compliant hostnames, including /, ?, , and @. Because req.host returns the full parsed value, applications that validate hosts using naive prefix or suffix checks can be...

Rack 安全漏洞

Rack is a modular Ruby web server interface developed by Rack authors. Versions of Rack prior to 3.1.21 and 3.2.6 contained security vulnerabilities. These vulnerabilities stemmed from the use of the AUTHORITY regular expression for parsing Host headers in Rack::Request, allowing illegal characte...

PT-2026-29924

Summary Rack::Multipart::Parserhandle mime head parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated Stringindex searches combined with Stringslice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An...

Rack 安全漏洞

Rack is a modular Ruby web server interface developed by the Rack open-source project. Versions of Rack prior to 2.2.23, 3.1.21, and 3.2.6 contained security vulnerabilities. These vulnerabilities stemmed from the use of greedy regular expressions by the multipart parser to extract boundary...

Rack 信息泄露漏洞

Rack is a modular Ruby web server interface developed by Rack authors. Versions of Rack prior to 2.2.23, 3.1.21, and 3.2.6 contained an information leakage vulnerability. This vulnerability stemmed from Rack::Static’s use of simple string prefix checks to determine whether a request should be...

PT-2026-29813

Name of the Vulnerable Software and Affected Versions Rack versions prior to 2.2.23, 3.1.21, and 3.2.6 Description Rack’s Rack::Staticapplicable rules component evaluates header rules against the raw URL-encoded PATH INFO, while the file-serving path is decoded. This allows an attacker to bypass...

PT-2026-29841

Name of the Vulnerable Software and Affected Versions Rack versions 3.2.0 through 3.2.5 Description Rack’s Rack::Multipart::Parser incorrectly unfolds folded multipart part headers. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values...

Rack 安全漏洞

Rack is a modular Ruby web server interface developed by Rack authors. There were security vulnerabilities in versions of Rack from 3.0.0.beta1 to 3.1.21, as well as in versions from 3.2.0 to 3.2.6. These vulnerabilities stemmed from improper parsing of forwarded headers, which could lead to...

PT-2026-29922

Summary Rack::Sendfilemap 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...

PT-2026-29925

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...

PT-2026-29819

Name of the Vulnerable Software and Affected Versions Rack versions prior to 2.2.23, 3.1.21, and 3.2.6 Description Rack’s Rack::Filesfail function incorrectly calculates the Content-Length response header using Stringsize instead of Stringbytesize. This occurs when the response body contains...

Rack's multipart header parsing allows Denial of Service via escape-heavy quoted parameters

Summary Rack::Multipart::Parserhandlemimehead parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated Stringindex searches combined with Stringslice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An unauthenticat...

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...

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,...

Rack:: Static header_rules bypass via URL-encoded paths

Summary Rack::Staticapplicablerules evaluates several headerrules types against the raw URL-encoded PATHINFO, while the underlying file-serving path is decoded before the file is served. As a result, a request for a URL-encoded variant of a static path can serve the same file without the headers...

PT-2026-29817

Name of the Vulnerable Software and Affected Versions Rack versions prior to 2.2.23, 3.1.21, and 3.2.6 Description Rack's Rack::Multipart::Parser does not limit the size of multipart uploads when a Content-Length header is not present, such as with HTTP chunked transfer encoding. Specifically, wh...