CVE-2026-34835

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{"affected": [{"affectedData": [{"product": "rack", "vendor": "rack", "versions": [{"status": "affected", "version": ">= 3.0.0.beta1, < 3.1.21"}, {"status": "affected", "version": ">= 3.2.0, < 3.2.6"}]}], "source": "security-advisories@github.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*", "matchCriteriaId": "6948AAA6-873D-46BA-AA22-4C81138128E1", "versionEndExcluding": "3.1.21", "versionStartIncluding": "3.0.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*", "matchCriteriaId": "3FB592AD-E826-49BE-AC6D-E5F55FDCC96E", "versionEndExcluding": "3.2.6", "versionStartIncluding": "3.2.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21, and 3.2.0 to before 3.2.6, Rack::Request parses the Host header using an AUTHORITY regular expression that accepts characters not permitted in RFC-compliant hostnames, including /, ?, #, and @. Because req.host returns the full parsed value, applications that validate hosts using naive prefix or suffix checks can be bypassed. This can lead to host header poisoning in applications that use req.host, req.url, or req.base_url for link generation, redirects, or origin validation. This issue has been patched in versions 3.1.21 and 3.2.6."}, {"lang": "es", "value": "Rack es una interfaz modular de servidor web Ruby. Desde las versiones 3.0.0.beta1 hasta antes de la 3.1.21, y de la 3.2.0 hasta antes de la 3.2.6, Rack::Request analiza el encabezado Host utilizando una expresi\u00f3n regular AUTHORITY que acepta caracteres no permitidos en nombres de host conformes a RFC, incluyendo /, ?, # y @. Debido a que req.host devuelve el valor analizado completo, las aplicaciones que validan hosts utilizando comprobaciones ingenuas de prefijo o sufijo pueden ser eludidas. Esto puede llevar a un envenenamiento del encabezado Host en aplicaciones que utilizan req.host, req.url o req.base_url para la generaci\u00f3n de enlaces, redirecciones o validaci\u00f3n de origen. Este problema ha sido parcheado en las versiones 3.1.21 y 3.2.6."}], "id": "CVE-2026-34835", "lastModified": "2026-07-24T21:10:00.143", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 4.8, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.2, "impactScore": 2.5, "source": "security-advisories@github.com", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 2.5, "source": "nvd@nist.gov", "type": "Primary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-34835", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-04-02T17:43:54.517566Z", "version": "2.0.3"}}]}, "published": "2026-04-02T18:16:33.967", "references": [{"source": "security-advisories@github.com", "tags": ["Exploit", "Mitigation", "Vendor Advisory"], "url": "https://github.com/rack/rack/security/advisories/GHSA-g2pf-xv49-m2h5"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-1286"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{"bugzilla": {"description": "rack: Rack: Host header poisoning due to malformed Host header bypasses validation", "id": "2454482", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2454482"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.8", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N", "status": "draft"}, "cwe": "CWE-1286", "details": ["Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21, and 3.2.0 to before 3.2.6, Rack::Request parses the Host header using an AUTHORITY regular expression that accepts characters not permitted in RFC-compliant hostnames, including /, ?, #, and @. Because req.host returns the full parsed value, applications that validate hosts using naive prefix or suffix checks can be bypassed. This can lead to host header poisoning in applications that use req.host, req.url, or req.base_url for link generation, redirects, or origin validation. This issue has been patched in versions 3.1.21 and 3.2.6.", "A flaw was found in Rack. A remote attacker could exploit this by sending a specially crafted Host header containing characters not permitted in standard hostnames. This malformed header bypasses hostname validation in applications using Rack::Request, leading to host header poisoning. This can enable an attacker to manipulate links, redirects, or origin validation within affected applications."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability."}, "name": "CVE-2026-34835", "package_state": [{"cpe": "cpe:/a:redhat:logging:5", "fix_state": "Fix deferred", "package_name": "openshift-logging/cluster-logging-operator-bundle", "product_name": "Logging Subsystem for Red Hat OpenShift"}, {"cpe": "cpe:/a:redhat:logging:5", "fix_state": "Fix deferred", "package_name": "openshift-logging/cluster-logging-rhel9-operator", "product_name": "Logging Subsystem for Red Hat OpenShift"}, {"cpe": "cpe:/a:redhat:logging:5", "fix_state": "Fix deferred", "package_name": "openshift-logging/eventrouter-rhel9", "product_name": "Logging Subsystem for Red Hat OpenShift"}, {"cpe": "cpe:/a:redhat:logging:5", "fix_state": "Fix deferred", "package_name": "openshift-logging/fluentd-rhel9", "product_name": "Logging Subsystem for Red Hat OpenShift"}, {"cpe": "cpe:/a:redhat:logging:5", "fix_state": "Fix deferred", "package_name": "openshift-logging/log-file-metric-exporter-rhel9", "product_name": "Logging Subsystem for Red Hat OpenShift"}, {"cpe": "cpe:/a:redhat:logging:5", "fix_state": "Fix deferred", "package_name": "openshift-logging/logging-view-plugin-rhel9", "product_name": "Logging Subsystem for Red Hat OpenShift"}, {"cpe": "cpe:/a:redhat:logging:5", "fix_state": "Fix deferred", "package_name": "openshift-logging/vector-rhel9", "product_name": "Logging Subsystem for Red Hat OpenShift"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp20/backend", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp20/system", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp21/backend", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp21/system", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp21/zync", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp22/backend", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp22/system", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp22/zync", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp24/backend", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp24/system", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp24/zync", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp25/backend", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp25/system", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp25/zync", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp26/backend", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp26/system", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp26/zync", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp2/backend-rhel7", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", 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2"}, {"cpe": "cpe:/a:redhat:red_hat_3scale_amp:2", "fix_state": "Fix deferred", "package_name": "3scale-amp2/zync-rhel9", "product_name": "Red Hat 3scale API Management Platform 2"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "pcs", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Fix deferred", "package_name": "pcs", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "pcs", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "pcs", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "rhel9/ruby-30", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "rhel9/ruby-33", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "ubi9/ruby-30", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "ubi9/ruby-33", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-04-02T17:09:07Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-34835\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-34835\nhttps://github.com/rack/rack/security/advisories/GHSA-g2pf-xv49-m2h5"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"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": "2026-04-03T22:28:03.240163+00:00", "value": {"mitigation_remediation": ["Upgrade Rack to version 3.1.21 or later, or 3.2.6 or later, to apply the fix.", "Verify that your application performs proper host validation and does not rely solely on naive prefix/suffix checks.", "Implement additional safeguards by sanitizing the Host header to remove characters such as /, ?, #, and @ before using it for redirects or link generation."], "summary": {"action": "Immediate Patch", "impact": "Host header poisoning and allowlist bypass via invalid characters"}, "threat_synthesis": {"affected_systems": "The affected product is rack:rack. Versions from 3.0.0.beta1 up to, but not including, 3.1.21 and 3.2.0 up to, but not including, 3.2.6 are vulnerable. These patches are included in 3.1.21 and 3.2.6.", "description_and_impact": "Rack is a modular Ruby web server interface. The vulnerability allows Rack::Request to parse the Host header with a pattern that accepts characters not permitted in RFC-compliant hostnames, such as /, ?, #, and @. Applications that use simple prefix or suffix checks on the Host header can therefore be tricked into accepting forged host values, leading to host header poisoning that may affect link generation, redirects, or origin validation. The weakness is an example of host header injection (CWE-1286).", "risk_and_exploitability": "The CVSS score of 4.8 indicates a moderate severity, with an EPSS score below 1\u202f% showing low probability of exploitation. The vulnerability is not listed in CISA\u2019s KEV catalog, so no large\u2011scale exploit data is available. Attackers would need to send a crafted HTTP request with a Host header containing invalid characters; the impact would be confined to the affected application\u2019s request handling and any downstream redirects or URL generation."}}}}, "created": "2026-04-03T07:32:24.276589+00:00", "updated": "2026-04-07T07:55:52.245715+00:00", "vendors": ["rack", "rack$PRODUCT$rack"]}