CVE-2026-8238

Concrete CMS 9.5.0 and below is vulnerable to IDOR. The '/ccm/frontend/conversations/message_page' endpoint returns the full content of any conversation message. An unauthenticated attacker can enumerate all conversation messages, including messages from restricted pages, member-only areas, and the moderation queue. File attachments with download URLs are also exposed. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with Vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Tristan Madani for reporting.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes	Release Notes

Configurations

Configuration 1 (hide)

cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-05-21 22:16

Updated : 2026-07-23 16:10

NVD link : CVE-2026-8238

Mitre link : CVE-2026-8238

CVE.ORG link : CVE-2026-8238

JSON object : View

Products Affected

concretecms

concrete_cms

CWE

CWE-862

Missing Authorization

{"id": "CVE-2026-8238", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-8238", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-05-22T12:30:51.504751Z"}}], "cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "LOW"}, "impactScore": 1.4, "exploitabilityScore": 3.9}], "cvssMetricV40": [{"type": "Secondary", "source": "ff5b8ace-8b95-4078-9743-eac1ca5451de", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 6.3, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/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": "PRESENT", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "LOW", "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": "ff5b8ace-8b95-4078-9743-eac1ca5451de", "affectedData": [{"repo": "https://github.com/concretecms/concretecms", "vendor": "Concrete CMS", "product": "Concrete CMS", "versions": [{"status": "affected", "version": "5.0", "versionType": "git", "lessThanOrEqual": "9.5.0"}], "collectionURL": "https://github.com/concretecms/concretecms", "defaultStatus": "unaffected"}]}], "published": "2026-05-21T22:16:49.893", "references": [{"url": "https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes", "tags": ["Release Notes"], "source": "ff5b8ace-8b95-4078-9743-eac1ca5451de"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "ff5b8ace-8b95-4078-9743-eac1ca5451de", "description": [{"lang": "en", "value": "CWE-862"}]}], "descriptions": [{"lang": "en", "value": "Concrete CMS 9.5.0 and below is vulnerable to IDOR.\u00a0The\u00a0'/ccm/frontend/conversations/message_page'\u00a0endpoint returns the full content of any conversation message. An unauthenticated attacker can enumerate all conversation messages, including messages from restricted pages, member-only areas, and the moderation queue. File attachments with download URLs are also exposed.\u00a0The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of\u00a06.3 with Vector\u00a0CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Tristan Madani for reporting."}, {"lang": "es", "value": "Concrete CMS 9.5.0 y versiones anteriores es vulnerable a IDOR. El endpoint '/ccm/frontend/conversations/message_page' devuelve el contenido completo de cualquier mensaje de conversaci\u00f3n. Un atacante no autenticado puede enumerar todos los mensajes de conversaci\u00f3n, incluyendo mensajes de p\u00e1ginas restringidas, \u00e1reas solo para miembros y la cola de moderaci\u00f3n. Archivos adjuntos con URLs de descarga tambi\u00e9n est\u00e1n expuestos. El equipo de seguridad de Concrete CMS otorg\u00f3 a esta vulnerabilidad una puntuaci\u00f3n CVSS v.4.0 de 6.3 con el Vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Gracias a Tristan Madani por el informe."}], "lastModified": "2026-07-23T16:10:00.137", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "2E0D5AA2-E073-464B-9026-9A428B24ABFA", "versionEndExcluding": "9.5.1"}], "operator": "OR"}]}], "sourceIdentifier": "ff5b8ace-8b95-4078-9743-eac1ca5451de"}