Rack: Rack::Static header_rules bypass via URL-encoded paths_CVE-2026-34786

5.3 / 10

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Description

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.

Basic Information

ID CVE-2026-34786

Source GitHub_M

Published Apr 2, 2026 at 16:44

Modified Apr 3, 2026 at 17:38

Affected Product

Vendor rack

Product rack

Version < 2.2.23

Affected Versions rack rack < 2.2.23
rack rack >= 3.0.0.beta1, < 3.1.21
rack rack >= 3.2.0, < 3.2.6

CWE Classification

CWE-180

References

github.com /rack/rack/security/advisories/GHSA-q4qf-9j86-f5mh

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