CVE-2026-5388

{"id": "CVE-2026-5388", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-5388", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-08-26T16:07:56.131062Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 9.8, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 3.9}], "cvssMetricV40": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 9.3, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "disclosure@vulncheck.com", "affectedData": [{"vendor": "EmilStenstrom", "product": "justhtml", "versions": [{"status": "affected", "version": "0", "lessThan": "1.15.0", "versionType": "semver"}, {"status": "unaffected", "version": "1.15.0", "versionType": "semver"}], "packageURL": "pkg:pypi/justhtml", "defaultStatus": "unaffected"}]}], "published": "2026-08-23T14:16:53.470", "references": [{"url": "https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-c9vm-hv86-f23r", "source": "disclosure@vulncheck.com"}, {"url": "https://www.vulncheck.com/advisories/justhtml-before-multiple-security-issues", "source": "disclosure@vulncheck.com"}], "vulnStatus": "Deferred", "weaknesses": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "description": [{"lang": "en", "value": "CWE-20"}]}], "descriptions": [{"lang": "en", "value": "justhtml before 1.15.0 contains multiple security issues in URL sanitization helpers (clean_url_value/clean_url_in_js_string), HTML serialization, Markdown passthrough (html_passthrough=True), and several custom sanitization-policy edge cases. Depending on configuration, an attacker can bypass sanitization to inject active HTML and JavaScript \u2014 for example via encoded javascript: URLs, backslash-based relative URLs resolved as remote hosts, markup-breaking programmatic element/attribute names or HTML comments, raw </textarea> reintroduction through Markdown passthrough, or preserved <style>/<meta http-equiv=refresh>/<base href> tags in custom policies. Most custom-policy issues do not affect the default sanitize=True configuration; they primarily affect helper APIs, programmatic DOM construction, html_passthrough=True, and custom policies/transform pipelines."}, {"lang": "es", "value": "justhtml anterior a 1.15.0 contiene m\u00faltiples problemas de seguridad en los ayudantes de saneamiento de URL (clean_url_value/clean_url_in_js_string), serializaci\u00f3n HTML, paso a trav\u00e9s de Markdown (html_passthrough=True), y varios casos l\u00edmite de pol\u00edticas de saneamiento personalizadas. Dependiendo de la configuraci\u00f3n, un atacante puede eludir el saneamiento para inyectar HTML y JavaScript activos - por ejemplo, a trav\u00e9s de URL javascript: codificadas, URL relativas basadas en barras invertidas resueltas como hosts remotos, nombres de elementos/atributos program\u00e1ticos que rompen el marcado o comentarios HTML, reintroducci\u00f3n de </textarea> sin procesar a trav\u00e9s del paso a trav\u00e9s de Markdown, o etiquetas <style>/<meta http-equiv=refresh>/<base href> preservadas en pol\u00edticas personalizadas. La mayor\u00eda de los problemas de las pol\u00edticas personalizadas no afectan la configuraci\u00f3n predeterminada sanitize=True; afectan principalmente a las API auxiliares, la construcci\u00f3n program\u00e1tica del DOM, html_passthrough=True, y las pol\u00edticas personalizadas/pipelines de transformaci\u00f3n."}], "lastModified": "2026-10-12T16:10:00.220", "sourceIdentifier": "disclosure@vulncheck.com"}