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{"cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-34786", "lastModified": "2026-04-03T16:10:23.730", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 1.4, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-04-02T17:16:25.030", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/rack/rack/security/advisories/GHSA-q4qf-9j86-f5mh"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Undergoing Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-180"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,2.2.23)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[3.0.0.beta1,3.1.21)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[3.2.0,3.2.6)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "rack", "source": "cna", "vendor": "rack"}, "product": "rack", "vendor": "rack"}], "analysis": {"en": {"generated_at": "2026-04-02T23:16:44.992327+00:00", "value": {"mitigation_remediation": ["Update Rack to a patched release version 2.2.23 or newer, 3.1.21 or newer, or 3.2.6 or newer."], "summary": {"action": "Patch immediately", "impact": "Security header bypass"}, "threat_synthesis": {"affected_systems": "The vulnerability affects the Rack framework, specifically Rack::Static in versions earlier than 2.2.23, 3.1.21, and 3.2.6. Installing any of the patched releases mitigates the issue.", "description_and_impact": "Rack::Static evaluates header_rules against the raw URL\u2011encoded PATH_INFO, while the underlying file\u2011serving path is decoded before the file is served. This mismatch allows an attacker to request a URL\u2011encoded variant of a static path and receive the file without the security headers that the header_rules are intended to add. The result is a bypass of the desired response headers for static content.", "risk_and_exploitability": "The CVSS score is 5.3, indicating moderate severity. The flaw is not listed in the CISA KEV catalog and EPSS data is not available. The likely attack vector is a simple HTTP request with a URL\u2011encoded path; exploitation requires only network access to the target and no special prerequisites. The impact is confined to the loss of the intended security headers, without providing remote code execution or denial of service."}}}}, "created": "2026-04-03T07:32:34.842456+00:00", "updated": "2026-04-03T09:18:25.935259+00:00", "vendors": ["rack", "rack$PRODUCT$rack"]}