EUVD-2026-18384
GHSA-q4qf-9j86-f5mh
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Lifecycle Timeline
4Description
Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Static#applicable_rules evaluates several header_rules types against the raw URL-encoded PATH_INFO, 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 that header_rules were intended to apply. In deployments that rely on Rack::Static to attach security-relevant response headers to static content, this can allow an attacker to bypass those headers by requesting an encoded form of the path. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.
Analysis
Rack::Static fails to apply security-relevant response headers to URL-encoded variants of static file paths, allowing attackers to bypass header-based security controls by requesting percent-encoded forms of protected resources. This affects Rack versions prior to 2.2.23, 3.1.21, and 3.2.6, and is particularly dangerous in deployments relying on Rack::Static to enforce Content-Security-Policy, X-Frame-Options, or similar protective headers on static content. …
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