{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-126203", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-11-10T20:07:44.958Z", "datePublished": "2026-11-12T18:06:34.560Z", "dateUpdated": "2026-11-12T19:28:45.309Z"}, "containers": {"cna": {"title": "Loofah: Mutation XSS in the HTML5 scrubbers through unescaped attribute values", "problemTypes": [{"descriptions": [{"cweId": "CWE-79", "lang": "en", "description": "CWE-79: Improper Neutralization of Input During Web Page Generation", "type": "CWE"}]}, {"descriptions": [{"cweId": "CWE-116", "lang": "en", "description": "CWE-116: Improper Encoding or Escaping of Output", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.1, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/flavorjones/loofah/security/advisories/GHSA-h6v6-rg66-fqj4", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/flavorjones/loofah/security/advisories/GHSA-h6v6-rg66-fqj4"}, {"name": "https://github.com/flavorjones/loofah/pull/324", "tags": ["x_refsource_MISC"], "url": "https://github.com/flavorjones/loofah/pull/324"}, {"name": "https://github.com/sparklemotion/nokogiri/pull/3741", "tags": ["x_refsource_MISC"], "url": "https://github.com/sparklemotion/nokogiri/pull/3741"}, {"name": "https://github.com/flavorjones/loofah/commit/7ba1e7b77e043fb7dc832ef746fcbf83137135e6", "tags": ["x_refsource_MISC"], "url": "https://github.com/flavorjones/loofah/commit/7ba1e7b77e043fb7dc832ef746fcbf83137135e6"}, {"name": "https://github.com/sparklemotion/nokogiri/commit/635abc8d65c75d594ddf8957fbfbfd822c2c0dbd", "tags": ["x_refsource_MISC"], "url": "https://github.com/sparklemotion/nokogiri/commit/635abc8d65c75d594ddf8957fbfbfd822c2c0dbd"}, {"name": "https://github.com/flavorjones/loofah/releases/tag/v2.25.3", "tags": ["x_refsource_MISC"], "url": "https://github.com/flavorjones/loofah/releases/tag/v2.25.3"}, {"name": "https://github.com/sparklemotion/nokogiri/releases/tag/v1.19.5", "tags": ["x_refsource_MISC"], "url": "https://github.com/sparklemotion/nokogiri/releases/tag/v1.19.5"}], "affected": [{"vendor": "flavorjones", "product": "loofah", "versions": [{"version": ">= 2.21.0, < 2.25.3", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-11-12T18:06:34.560Z"}, "descriptions": [{"lang": "en", "value": "Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. From 2.21.0 until 2.25.3, Loofah's HTML5 APIs Loofah.html5_fragment, Loofah.html5_document, and the scrub_html5_* methods can emit sanitized output that a browser reparses as different markup when used with Nokogiri before 1.19.5, because those Nokogiri versions do not escape angle brackets in attribute values. MathML can place markup inside an allowed attribute so the reparsed output becomes live HTML. The :strip scrubber is affected in every browser, while :prune and :escape are affected in WebKit browsers. Loofah's HTML4 APIs, Loofah::Helpers.sanitize, :whitewash, rails-html-sanitizer's default configuration, and JRuby are not affected. This issue is fixed in version 2.25.3."}], "source": {"advisory": "GHSA-h6v6-rg66-fqj4", "discovery": "UNKNOWN"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-11-12T19:20:09.567928Z", "id": "CVE-2026-126203", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-11-12T19:28:45.309Z"}}]}}

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{"affected": [{"affectedData": [{"product": "loofah", "vendor": "flavorjones", "versions": [{"status": "affected", "version": ">= 2.21.0, < 2.25.3"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. From 2.21.0 until 2.25.3, Loofah's HTML5 APIs Loofah.html5_fragment, Loofah.html5_document, and the scrub_html5_* methods can emit sanitized output that a browser reparses as different markup when used with Nokogiri before 1.19.5, because those Nokogiri versions do not escape angle brackets in attribute values. MathML can place markup inside an allowed attribute so the reparsed output becomes live HTML. The :strip scrubber is affected in every browser, while :prune and :escape are affected in WebKit browsers. Loofah's HTML4 APIs, Loofah::Helpers.sanitize, :whitewash, rails-html-sanitizer's default configuration, and JRuby are not affected. This issue is fixed in version 2.25.3."}], "id": "CVE-2026-126203", "lastModified": "2026-11-12T22:09:39.233", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.1, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 2.7, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-126203", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-11-12T19:20:09.567928Z", "version": "2.0.3"}}]}, "published": "2026-11-12T19:16:56.517", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/flavorjones/loofah/commit/7ba1e7b77e043fb7dc832ef746fcbf83137135e6"}, {"source": "security-advisories@github.com", "url": "https://github.com/flavorjones/loofah/pull/324"}, {"source": "security-advisories@github.com", "url": "https://github.com/flavorjones/loofah/releases/tag/v2.25.3"}, {"source": "security-advisories@github.com", "url": "https://github.com/flavorjones/loofah/security/advisories/GHSA-h6v6-rg66-fqj4"}, {"source": "security-advisories@github.com", "url": "https://github.com/sparklemotion/nokogiri/commit/635abc8d65c75d594ddf8957fbfbfd822c2c0dbd"}, {"source": "security-advisories@github.com", "url": "https://github.com/sparklemotion/nokogiri/pull/3741"}, {"source": "security-advisories@github.com", "url": "https://github.com/sparklemotion/nokogiri/releases/tag/v1.19.5"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}, {"lang": "en", "value": "CWE-116"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

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