CVE-2026-34785

Summary

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.

Affected Software

VendorProductVersion RangeStatus
rackrack< 2.2.23affected
rackrack>= 3.0.0.beta1, < 3.1.21affected
rackrack>= 3.2.0, < 3.2.6affected

Weaknesses

  • CWE-187: CWE-187: Partial String Comparison
  • CWE-200: CWE-200: Exposure of Sensitive Information to an Unauthorized Actor

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: yes
    • Technical Impact: partial

github.com/rack/rack: Rack: Information disclosure via incorrect static file serving prefix check

Additional References

References