CVE-2026-3787

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A high degree of complexity is needed for the attack. The exploitability is reported as difficult. The vendor was contacted early about this disclosure but did not respond in any way."}, {"lang": "es", "value": "Se ha identificado una debilidad en UltraVNC 1.6.4.0 en Windows. Esto afecta a una funci\u00f3n desconocida en la biblioteca cryptbase.dll del componente Servicio de Windows. Esta manipulaci\u00f3n causa una ruta de b\u00fasqueda incontrolada. El ataque requiere acceso local. Se necesita un alto grado de complejidad para el ataque. La explotabilidad se reporta como dif\u00edcil. El proveedor fue contactado tempranamente sobre esta divulgaci\u00f3n pero no respondi\u00f3 de ninguna manera."}], "id": "CVE-2026-3787", "lastModified": "2026-06-17T10:44:13.353", "metrics": {"cvssMetricV2": [{"acInsufInfo": false, "baseSeverity": "MEDIUM", "cvssData": {"accessComplexity": "HIGH", "accessVector": "LOCAL", "authentication": "SINGLE", "availabilityImpact": "COMPLETE", "baseScore": 6.0, "confidentialityImpact": "COMPLETE", "integrityImpact": "COMPLETE", "vectorString": "AV:L/AC:H/Au:S/C:C/I:C/A:C", "version": "2.0"}, "exploitabilityScore": 1.5, "impactScore": 10.0, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "source": "cna@vuldb.com", "type": "Secondary", "userInteractionRequired": false}], "cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.0, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.0, "impactScore": 5.9, "source": "cna@vuldb.com", "type": "Secondary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "HIGH", "attackRequirements": "NONE", "attackVector": "LOCAL", "availabilityRequirement": "NOT_DEFINED", "baseScore": 6.4, "baseSeverity": "MEDIUM", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "PROOF_OF_CONCEPT", "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": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/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": "cna@vuldb.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-3787", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-03-10T20:25:13.729869Z", "version": "2.0.3"}}]}, "published": "2026-03-08T23:15:50.690", "references": [{"source": "cna@vuldb.com", "tags": ["Permissions Required"], "url": "https://drive.google.com/file/d/14ixv_1i4D2VrZWyl4RKsvFcN1AMF_qNx/view"}, {"source": "cna@vuldb.com", "tags": ["Permissions Required", "VDB Entry"], "url": "https://vuldb.com/?ctiid.349754"}, {"source": "cna@vuldb.com", "tags": ["Third Party Advisory", "VDB Entry"], "url": "https://vuldb.com/?id.349754"}, {"source": "cna@vuldb.com", "tags": ["Third Party Advisory", "VDB Entry"], "url": "https://vuldb.com/?submit.767257"}], "sourceIdentifier": "cna@vuldb.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-426"}, {"lang": "en", "value": "CWE-427"}], "source": "cna@vuldb.com", "type": "Secondary"}, {"description": [{"lang": "en", "value": "CWE-426"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "1.6.4.0"}}], "enrichment": {"confidence": 95.0, "confidence_source": "inferred", "scores": [{"score": 95.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "UltraVNC", "source": "cna", "vendor": "n/a"}, "product": "ultravnc", "vendor": "ultravnc"}], "analysis": {"en": {"generated_at": "2026-04-16T10:27:15.256370+00:00", "value": {"mitigation_remediation": ["Upgrade UltraVNC to the latest released version that addresses this issue", "If an update is unavailable, run the UltraVNC service with the lowest privilege level and tightly control the directories it can probe for DLLs", "Configure Windows to enforce a safe DLL search order (e.g., use SetDefaultDllDirectories) or restrict the system PATH for the service process"], "summary": {"action": "Patch", "impact": "Uncontrolled DLL search path can enable local execution of malicious code via cryptbase.dll in UltraVNC 1.6.4.0 on Windows"}, "threat_synthesis": {"affected_systems": "This problem affects UltraVNC 1.6.4.0 running on Windows platforms. The vulnerable component is part of the UltraVNC service bundle; users with Windows operating systems that host this specific version of UltraVNC are susceptible.", "description_and_impact": "The vulnerability lies in an unknown function within cryptbase.dll exposed by the UltraVNC Windows Service. The flaw permits an attacker with local access to manipulate the DLL search path, potentially causing the service to load a malicious DLL and execute arbitrary code. This weakness corresponds to CWE\u2011426 and CWE\u2011427, illustrating an untrusted or uncontrolled search path that can lead to DLL hijacking. The description indicates that the attack requires high complexity and is considered difficult to exploit, which limits immediate threat but still permits a serious compromise if achieved.", "risk_and_exploitability": "The CVSS score of 7.3 marks it as high severity. However, the EPSS score is less than 1%, indicating a low probability of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog. The limited attacker capability (local access only) and the stated difficulty in exploitation suggest that while the risk to organizational security is significant, active attacks are currently few."}}}}, "created": "2026-03-09T10:02:39.636279+00:00", "updated": "2026-04-16T10:30:16.176013+00:00", "vendors": ["ultravnc", "ultravnc$PRODUCT$ultravnc"]}