{"cve":"CVE-2026-34786","nvd":{"published":"2026-04-02T17:16:25.030","modified":"2026-07-24T21:10:00.143","status":"Analyzed","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","score":5.3},"cwes":["CWE-180"],"references":["https://github.com/rack/rack/security/advisories/GHSA-q4qf-9j86-f5mh"],"products":["rack:rack"],"source":"nvd","synced_at":"2026-10-19T22:28:18.033120106+00:00"},"epss":{"cve":"CVE-2026-34786","score":0.00202,"percentile":0.10209,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-q4qf-9j86-f5mh","url":"https://osv.dev/vulnerability/GHSA-q4qf-9j86-f5mh","summary":"Rack:: Static header_rules bypass via URL-encoded paths","modified":"2026-09-10T03:51:02.740705385Z","packages":[{"ecosystem":"RubyGems","name":"rack","purl":"pkg:gem/rack","ranges":["<2.2.23"],"fixed":["2.2.23"]},{"ecosystem":"RubyGems","name":"rack","purl":"pkg:gem/rack","ranges":[">=3.0.0.beta1 <3.1.21"],"fixed":["3.1.21"]},{"ecosystem":"RubyGems","name":"rack","purl":"pkg:gem/rack","ranges":[">=3.2.0 <3.2.6"],"fixed":["3.2.6"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}