CVE-2026-34786

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.

Affected products

Linuxmint, Rack, Red Os, Ubuntu

Rack

< 2.2.23, 3.1.21, 3.2.6

Fix

Available

CVSS 3.1

5.3 MEDIUM

EPSS

0.2% (9th percentile)

Weakness

CWE-180

NVD status

Analyzed

Published

2026-04-02

No exploit for CVE-2026-34786 has been indexed yet. Our index is built from live traffic and upstream syncs, so this page can only say what it knows — not that no exploit exists.