CVE-2026-39426

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{"affected": [{"affectedData": [{"product": "MaxKB", "vendor": "1Panel-dev", "versions": [{"status": "affected", "version": "< 2.8.0"}]}], "source": "security-advisories@github.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:maxkb:maxkb:*:*:*:*:-:*:*:*", "matchCriteriaId": "8BB376B6-4E9C-4801-9D33-5BF858C857D2", "versionEndExcluding": "2.8.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain a Stored Cross-Site Scripting (XSS) vulnerability where the frontend's MdRenderer.vue component parses custom <iframe_render> tags from LLM responses or Application Prologue configurations, bypassing standard Markdown sanitization and XSS filtering. The unsanitized HTML content is passed to the IframeRender.vue component, which renders it directly into an <iframe> via the srcdoc attribute configured with sandbox=\"allow-scripts allow-same-origin\". This can be a dangerous combination, allowing injected scripts to escape the iframe and execute JavaScript in the parent window using window.parent. Since the Prologue is rendered for any user visiting an application's chat interface, this results in a high-impact Stored XSS that can lead to session hijacking, unauthorized actions, and sensitive data exposure. This issue has been fixed in version 2.8.0."}, {"lang": "es", "value": "MaxKB es un asistente de IA de c\u00f3digo abierto para empresas. Las versiones 2.7.1 y anteriores contienen una vulnerabilidad de Stored Cross-Site Scripting (XSS) donde el componente MdRenderer.vue del frontend analiza etiquetas personalizadas [iframe_tag] de respuestas de LLM o configuraciones de Application Prologue, omitiendo la sanitizaci\u00f3n est\u00e1ndar de Markdown y el filtrado de XSS. El contenido HTML no sanitizado se pasa al componente IframeRender.vue, que lo renderiza directamente en un [iframe_tag] a trav\u00e9s del atributo srcdoc configurado con sandbox=\u201callow-scripts allow-same-origin\u201d. Esto puede ser una combinaci\u00f3n peligrosa, permitiendo que los scripts inyectados escapen del iframe y ejecuten JavaScript en la ventana padre usando window.parent. Dado que el Pr\u00f3logo se renderiza para cualquier usuario que visita la interfaz de chat de una aplicaci\u00f3n, esto resulta en un Stored XSS de alto impacto que puede llevar al secuestro de sesi\u00f3n, acciones no autorizadas y exposici\u00f3n de datos sensibles. Este problema ha sido solucionado en la versi\u00f3n 2.8.0."}], "id": "CVE-2026-39426", "lastModified": "2026-10-26T21:10:00.170", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.4, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.3, "impactScore": 2.7, "source": "nvd@nist.gov", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 5.1, "baseSeverity": "MEDIUM", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "LOW", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "LOW", "subIntegrityImpact": "LOW", "userInteraction": "PASSIVE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/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", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-39426", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-04-16T13:23:08.165364Z", "version": "2.0.3"}}]}, "published": "2026-04-14T02:16:05.460", "references": [{"source": "security-advisories@github.com", "tags": ["Release Notes"], "url": "https://github.com/1Panel-dev/MaxKB/releases/tag/v2.8.0"}, {"source": "security-advisories@github.com", "tags": ["Vendor Advisory"], "url": "https://github.com/1Panel-dev/MaxKB/security/advisories/GHSA-q2qg-43vq-f2wv"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,2.8.0)"}}], "enrichment": {"confidence": 86.0, "confidence_source": "matching", "scores": [{"score": 86.0, "source": "matching"}]}, "original": {"product": "MaxKB", "source": "cna", "vendor": "1Panel-dev"}, "product": "maxkb", "vendor": "1panel"}], "analysis": {"en": {"generated_at": "2026-04-14T03:51:01.379368+00:00", "value": {"mitigation_remediation": ["Upgrade MaxKB to version 2.8.0 or later to fully eliminate the flaw.", "If an immediate upgrade is not possible, disable or remove the use of <iframe_render> tags in the prologue configuration and sanitize all LLM output before rendering.", "Consider restricting configuration write access to trusted administrators to prevent injection of malicious tags."], "summary": {"action": "Patch Now", "impact": "Stored XSS"}, "threat_synthesis": {"affected_systems": "The vulnerability affects the 1Panel\u2011dev MaxKB product for all releases through 2.7.1. Any deployment that stores unfiltered LLM output or uses custom prologue settings is vulnerable; the flaw is fixed starting with version 2.8.0.", "description_and_impact": "MaxKB, an open\u2011source AI assistant, contains a stored cross\u2011site scripting flaw in versions 2.7.1 and earlier. The front\u2011end component that renders LLM responses and application prologue configurations accepts custom <iframe_render> tags without sanitization. These tags are passed to a dedicated renderer that embeds the supplied HTML into an <iframe> using the srcdoc attribute. The sandbox on that iframe allows scripts to run and escape via window.parent, giving attackers a powerful route to execute JavaScript in the parent page.", "risk_and_exploitability": "The CVSS score of 5.1 labels the issue as medium severity, and no EPSS estimate is available. Because the exploit merely requires the insertion of a malicious <iframe_render> tag into stored content, the barrier to attack is low for anyone with the ability to modify LLM output or configure the application prologue. The flaw is not listed in CISA's Known Exploited Vulnerabilities catalog, but its stored nature means that all users who view the compromised chat can be affected, allowing session hijacking, unauthorized actions, and data exposure."}}}}, "created": "2026-04-14T16:16:07.581424+00:00", "updated": "2026-04-14T16:31:04.101082+00:00", "vendors": ["1panel", "1panel$PRODUCT$maxkb"]}