CVE-2026-40873

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{"affected": [{"affectedData": [{"product": "mailcow-dockerized", "vendor": "mailcow", "versions": [{"status": "affected", "version": "< 2026-03b"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "mailcow: dockerized is an open source groupware/email suite based on docker. In versions prior to 2026-03b, the Quarantine details modal injects attachment filenames into HTML without escaping, allowing arbitrary HTML/JS execution. An attacker can deliver an email with a crafted attachment name so that when an admin views the quarantine item, JavaScript executes in their browser, taking over their account. Version 2026-03b fixes the vulnerability."}, {"lang": "es", "value": "mailcow: dockerized es una suite de groupware/correo electr\u00f3nico de c\u00f3digo abierto basada en docker. En versiones anteriores a la 2026-03b, el modal de detalles de Cuarentena inyecta nombres de archivo adjuntos en HTML sin escapar, permitiendo la ejecuci\u00f3n arbitraria de HTML/JS. Un atacante puede entregar un correo electr\u00f3nico con un nombre de archivo adjunto manipulado de modo que cuando un administrador ve el elemento en cuarentena, JavaScript se ejecuta en su navegador, tomando el control de su cuenta. La versi\u00f3n 2026-03b corrige la vulnerabilidad."}], "id": "CVE-2026-40873", "lastModified": "2026-10-26T21:10:00.170", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 8.9, "baseSeverity": "HIGH", "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": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "HIGH", "subIntegrityImpact": "HIGH", "userInteraction": "PASSIVE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/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": "HIGH", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-40873", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-04-21T19:39:14.654574Z", "version": "2.0.3"}}]}, "published": "2026-04-21T20:17:00.820", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-2xjc-rg88-jvpp"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "url": "https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-2xjc-rg88-jvpp"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}, {"lang": "en", "value": "CWE-80"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,2026-03b)"}}], "enrichment": {"confidence": 82.0, "confidence_source": "matching", "scores": [{"score": 95.0, "source": "inferred"}, {"score": 82.0, "source": "matching"}]}, "original": {"product": "mailcow-dockerized", "source": "cna", "vendor": "mailcow"}, "product": "mailcow_dockerized", "vendor": "mailcow"}], "analysis": {"en": {"generated_at": "2026-04-22T06:45:27.103446+00:00", "value": {"mitigation_remediation": ["Upgrade mailcow\u2011dockerized to version 2026\u201103b or later, which eliminates the unescaped rendering of attachment filenames.", "If possible, disable or restrict the Quarantine interface for untrusted mail until the upgrade is completed.", "Configure a strict content\u2011security\u2011policy header on the web admin interface to block inline JavaScript, reducing the risk of XSS exploitation."], "summary": {"action": "Immediate Patch", "impact": "Stored Cross\u2011Site Scripting that allows an attacker to execute arbitrary JavaScript in a web admin\u2019s browser, leading to account takeover"}, "threat_synthesis": {"affected_systems": "The flaw affects the mailcow\u2011dockerized suite. Any deployment of the open source groupware/email system that has not upgraded beyond the 2026\u201103b release is vulnerable.", "description_and_impact": "In mailcow\u2011dockerized versions before 2026\u201103b, the Quarantine details modal injects attachment filenames directly into the page\u2019s HTML without escaping. An attacker can craft an email with a malicious attachment name, and when an administrator opens the quarantine record, the browser executes the injected code. This results in a complete compromise of the administrator\u2019s account and any privileges the web interface confers.", "risk_and_exploitability": "The CVSS score of 8.9 indicates high severity. The EPSS score is not available, but the vulnerability is known to be actionable and is not yet listed in CISA\u2019s KEV catalog, suggesting exploitation is possible yet not widely observed. Likely attack vectors involve the attacker sending a crafted email and the administrator subsequently viewing the quarantine modal in a browser."}}}}, "created": "2026-04-22T07:00:12.116745+00:00", "updated": "2026-04-22T11:45:48.863560+00:00", "vendors": ["mailcow", "mailcow$PRODUCT$mailcow_dockerized"]}