Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, 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 "/css-backup.sql". As a result, files under the static root whose names merely share the configured prefix may be served unintentionally, leading to information disclosure. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.
Use CWE-187, Rack vendor hub and Rack product page to widen CVE-2026-34785 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2026-34827, CVE-2026-34829 and CVE-2026-34830 for nearby disclosures in the same product family.