CVE-2026-34763: Rack

Medium severity, CVSS 5.3. EPSS: 0.3% chance of exploitation in the next 30 days.

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, 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 path in the HTML output. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

Affected products

• Rack Rack: before 2.2.23 (fixed in 2.2.23); from 3.0.0, before 3.1.21 (fixed in 3.1.21); from 3.2.0, before 3.2.6 (fixed in 3.2.6)

Published 2026-04-02. Last modified 2026-07-24.