{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-19820", "assignerOrgId": "4ac701fe-44e9-4bcd-9585-dd6449257611", "state": "PUBLISHED", "assignerShortName": "Bugcrowd", "dateReserved": "2026-08-14T05:28:19.979Z", "datePublished": "2026-09-01T00:13:03.935Z", "dateUpdated": "2026-09-01T00:13:03.935Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "4ac701fe-44e9-4bcd-9585-dd6449257611", "shortName": "Bugcrowd", "dateUpdated": "2026-09-01T00:13:03.935Z"}, "title": "Backblaze Client for Windows Improper Link Resolution Vulnerability", "problemTypes": [{"descriptions": [{"lang": "en", "description": "CWE-59 Improper Link Resolution Before File Access"}]}], "affected": [{"vendor": "Backblaze", "product": "Backblaze Client", "platforms": ["Windows"], "versions": [{"version": "10.0.0.1029", "status": "affected", "versionType": "custom"}, {"version": "10.0.1.10307", "status": "affected", "versionType": "custom"}, {"version": "10.0.2.1047", "status": "affected", "versionType": "custom"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "A vulnerability in the Backblaze Client allows a local user to make the system not bootable by creating a link from Backblaze's folder to Windows OS system files during a backup. Successful exploitation requires an administrator-level system change that results in the absence of specific Windows OS security controls. This vulnerability is due to improper link resolution."}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"baseScore": 5.8, "baseSeverity": "MEDIUM", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:L", "version": "4.0"}}], "credits": [{"lang": "en", "value": "TrendAI Zero Day Initiative", "type": "coordinator"}, {"lang": "en", "value": "hamdi", "type": "finder"}], "references": [{"url": "https://www.backblaze.com/computer-backup/docs/backup-client-release-notes-windows"}, {"url": "https://www.backblaze.com/status/update"}]}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "platforms": ["Windows"], "product": "Backblaze Client", "vendor": "Backblaze", "versions": [{"status": "affected", "version": "10.0.0.1029", "versionType": "custom"}, {"status": "affected", "version": "10.0.1.10307", "versionType": "custom"}, {"status": "affected", "version": "10.0.2.1047", "versionType": "custom"}]}], "source": "4ac701fe-44e9-4bcd-9585-dd6449257611"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "A vulnerability in the Backblaze Client allows a local user to make the system not bootable by creating a link from Backblaze's folder to Windows OS system files during a backup. Successful exploitation requires an administrator-level system change that results in the absence of specific Windows OS security controls. This vulnerability is due to improper link resolution."}], "id": "CVE-2026-19820", "lastModified": "2026-09-01T01:16:33.137", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 7.8, "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": "LOW", "subConfidentialityImpact": "HIGH", "subIntegrityImpact": "LOW", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:L/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": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "4ac701fe-44e9-4bcd-9585-dd6449257611", "type": "Secondary"}]}, "published": "2026-09-01T01:16:33.137", "references": [{"source": "4ac701fe-44e9-4bcd-9585-dd6449257611", "url": "https://www.backblaze.com/computer-backup/docs/backup-client-release-notes-windows"}, {"source": "4ac701fe-44e9-4bcd-9585-dd6449257611", "url": "https://www.backblaze.com/status/update"}], "sourceIdentifier": "4ac701fe-44e9-4bcd-9585-dd6449257611", "vulnStatus": "Received"}

{}

{"affected": [{"configurations": [{"platform": ["windows"], "status": "affected", "versions": {"scheme": "generic", "value": "10.0.0.1029"}}, {"platform": ["windows"], "status": "affected", "versions": {"scheme": "generic", "value": "10.0.1.10307"}}, {"platform": ["windows"], "status": "affected", "versions": {"scheme": "generic", "value": "10.0.2.1047"}}], "enrichment": {"confidence": 84.0, "confidence_source": "matching", "scores": [{"score": 84.0, "source": "matching"}]}, "original": {"product": "Backblaze Client", "source": "cna", "vendor": "Backblaze"}, "product": "backblaze", "vendor": "backblaze"}], "created": "2026-09-01T01:30:03.408129+00:00", "updated": "2026-09-01T12:30:04.168431+00:00", "vendors": ["backblaze", "backblaze$PRODUCT$backblaze"], "weaknesses": ["CWE-272", "CWE-269", "CWE-20"]}