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 prefix matching can expose unintended files under the static root

Summary Rack::Static determines whether a request should be served as a static file using a simple string prefix check. When configured with URL prefixes such as "/css", it matches any request path that begins with that string, including unrelated paths such as "/css-config.env" or...

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 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...

CVE-2026-34829: Uncontrolled Resource Consumption

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, 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 transfe...

PT-2026-29923

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,...

CVE-2026-26962: Improper Neutralization of CRLF Sequences

Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, 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 o...

CVE-2026-34830: Permissive Regular Expression

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, 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...

PT-2026-29808

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 uses a greedy regular expression to extract the boundary parameter from multipart/form-data. When a Content-Type header contains multiple boundary...

PT-2026-29809

Name of the Vulnerable Software and Affected Versions Rack versions prior to 2.2.23, 3.1.21, and 3.2.6 Description Rack::Utils.select best encoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard entries. Because this method is used by...

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-2026-29817

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...

PT-2026-29818

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::Sendfilemap accel path function directly uses the X-Accel-Mapping request header value in a regular expression for rewriting file paths used with X-Accel-Redirect. Becau...

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...

PT-2026-29856

Name of the Vulnerable Software and Affected Versions Rack versions 3.0.0.beta1 through 3.1.21 and versions 3.2.0 through 3.2.6 Description Rack’s Rack::Multipart::Parserhandle mime head function parses quoted multipart parameters using repeated Stringindex searches and Stringslice! operations...

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...

Rack security vulnerabilities

Rack is a modular Ruby web server interface developed by Rack authors. Vulnerabilities exist in versions of Rack prior to 2.2.23, 3.1.21, and 3.2.6. These vulnerabilities stem from Rack::Sendfilemapaccelpath directly inserting the values of the X-Accel-Mapping request header into regular...

Mageia: Security Advisory (MGASA-2026-0075)

The remote host is missing an update for the SPDX-FileCopyrightText: 2026 Greenbone AG Some text descriptions might be excerpted from a referenced sources, and are Copyright C by the respective right holders. SPDX-License-Identifier: GPL-2.0-only ifdescription...

Updated ruby-rack packages fix security vulnerabilities

Rack has a Directory Traversal via Rack:Directory. CVE-2026-22860 Rack's Stored XSS in Rack::Directory via javascript: filenames rendered into anchor href. CVE-2026-25500...