CVE-2026-23518

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{"affected": [{"affectedData": [{"product": "fleet", "vendor": "fleetdm", "versions": [{"status": "affected", "version": ">= 4.78.0, < 4.78.3"}, {"status": "affected", "version": ">= 4.77.0, < 4.77.1"}, {"status": "affected", "version": ">= 4.76.0, < 4.76.2"}, {"status": "affected", "version": ">= 4.75.0, < 4.75.2"}, {"status": "affected", "version": "< 4.53.3"}]}], "source": "security-advisories@github.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:*", "matchCriteriaId": "58B2870D-823A-4862-A51B-B3F86C60D89B", "versionEndExcluding": "4.53.3", "vulnerable": true}, {"criteria": "cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:*", "matchCriteriaId": "E363A7DF-0880-44B8-82A6-0192D1D43471", "versionEndExcluding": "4.75.2", "versionStartIncluding": "4.75.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:*", "matchCriteriaId": "53B5B8B6-F8C9-45E2-A160-D5834B1F3D61", "versionEndExcluding": "4.76.2", "versionStartIncluding": "4.76.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:*", "matchCriteriaId": "B8118C02-5CB2-45D3-AE6E-90313FB29720", "versionEndExcluding": "4.78.3", "versionStartIncluding": "4.78.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:fleetdm:fleet:4.77.0:*:*:*:*:*:*:*", "matchCriteriaId": "AE525B6A-8AF1-4D33-8EE9-FFD6A1C4F3F8", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Fleet is open source device management software. In versions prior to 4.78.3, 4.77.1, 4.76.2, 4.75.2, and 4.53.3, a vulnerability in Fleet's Windows MDM enrollment flow could allow an attacker to submit forged authentication tokens that are not properly validated. Because JWT signatures were not verified, Fleet could accept attacker-controlled identity claims, enabling enrollment of unauthorized devices under arbitrary Azure AD user identities. Versions 4.78.3, 4.77.1, 4.76.2, 4.75.2, and 4.53.3 fix the issue. If an immediate upgrade is not possible, affected Fleet users should temporarily disable Windows MDM."}, {"lang": "es", "value": "Fleet es software de gesti\u00f3n de dispositivos de c\u00f3digo abierto. En versiones anteriores a 4.78.3, 4.77.1, 4.76.2, 4.75.2 y 4.53.3, una vulnerabilidad en el flujo de inscripci\u00f3n de MDM de Windows de Fleet podr\u00eda permitir a un atacante enviar tokens de autenticaci\u00f3n falsificados que no se validan correctamente. Debido a que las firmas JWT no se verificaban, Fleet podr\u00eda aceptar reclamaciones de identidad controladas por el atacante, permitiendo la inscripci\u00f3n de dispositivos no autorizados bajo identidades de usuario arbitrarias de Azure AD. Las versiones 4.78.3, 4.77.1, 4.76.2, 4.75.2 y 4.53.3 solucionan el problema. Si una actualizaci\u00f3n inmediata no es posible, los usuarios de Fleet afectados deber\u00edan deshabilitar temporalmente Windows MDM."}], "id": "CVE-2026-23518", "lastModified": "2026-06-17T10:21:42.850", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "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": 9.3, "baseSeverity": "CRITICAL", "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": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "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", "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-2026-23518", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-01-22T15:13:36.673554Z", "version": "2.0.3"}}]}, "published": "2026-01-21T22:15:50.140", "references": [{"source": "security-advisories@github.com", "tags": ["Patch"], "url": "https://github.com/fleetdm/fleet/commit/e225ef57912c8f4ac8977e24b5ebe1d9fd875257"}, {"source": "security-advisories@github.com", "tags": ["Vendor Advisory"], "url": "https://github.com/fleetdm/fleet/security/advisories/GHSA-63m5-974w-448v"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-347"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"analysis": {"en": {"generated_at": "2026-04-18T15:31:54.969592+00:00", "value": {"mitigation_remediation": ["Upgrade Fleet to a fixed release\u20144.78.3 or newer or the patched 4.77.1, 4.76.2, 4.75.2, or 4.53.3 versions, as provided in the vendor advisory.", "Until an upgrade is possible, disable the Windows MDM enrollment capability to prevent unauthorized device registration.", "Monitor device enrollment logs for signs of unauthorized enrollment attempts and investigate any suspicious activity."], "summary": {"action": "Immediate Patch", "impact": "Unauthorized Device Enrollment"}, "threat_synthesis": {"affected_systems": "Affected products are Fleet, the open source device management software, in versions 4.53.3, 4.75.2, 4.76.2, 4.77.1, and earlier releases before 4.78.3 (any version containing the unverified JWT logic). Users of these releases are at risk if the Windows MDM feature is enabled.", "description_and_impact": "The vulnerability is a JWT signature bypass in Fleet's Windows MDM enrollment flow that allows attackers to submit forged authentication tokens without signature verification. By crafting such tokens, an attacker can cause Fleet to enroll unauthorized devices under arbitrary Azure AD user identities.", "risk_and_exploitability": "The CVSS base score is 9.3, indicating a high severity. The EPSS score is reported as less than 1\u202f% and the vulnerability is not listed in the CISA KEV catalog. Inference indicates that the attack vector is remote, relying on the ability to reach the Windows MDM enrollment endpoint. Exploitation would require an attacker to be able to query this endpoint and provide a forged token, after which Fleet would add the device to the fleet under the claimed Azure AD identity. The likelihood of exploitation at present appears low due to the very low EPSS score, yet the impact remains severe if it were successfully leveraged."}}}}, "created": "2026-01-22T10:08:42.939227+00:00", "updated": "2026-04-18T15:45:04.264315+00:00", "vendors": ["fleetdm", "fleetdm$PRODUCT$fleet"]}