{"id":"CVE-2026-19820","aliases":["EUVD-2026-68916","GHSA-wf7j-r93f-5cvm"],"status":"published","title":"Backblaze Client for Windows Improper Link Resolution Vulnerability","description":"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.","severity":{"version":"4.0","score":5.8,"vector":"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.0049,"percentile":0.42641,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-59"],"published":"2026-09-01T00:13:03Z","modified":"2026-09-11T00:17:28Z","products":[{"vendor":"backblaze","product":"backblaze client"}],"references":[{"url":"https://www.backblaze.com/computer-backup/docs/backup-client-release-notes-windows"},{"url":"https://www.backblaze.com/status/update"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-19820"},{"url":"https://github.com/advisories/GHSA-wf7j-r93f-5cvm"}],"sources":{"cve":[{"id":"CVE-2026-19820","title":"Backblaze Client for Windows Improper Link Resolution Vulnerability","description":"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.","status":"published","published":"2026-09-01T00:13:03.935Z","modified":"2026-09-10T23:32:25.536Z","cvss":[{"version":"4.0","score":5.8,"vector":"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","level":"medium","assessor":"cna"}],"cwes":["CWE-59"],"updated_at":"2026-11-02T13:47:17.512524Z"}],"euvd":[{"id":"EUVD-2026-68916","description":"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.","status":"published","published":"2026-09-01T00:13:03Z","modified":"2026-09-10T23:32:25Z","cvss":[{"version":"4.0","score":5.8,"vector":"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","level":"medium"}],"updated_at":"2026-11-02T17:28:23.364345Z"}],"ghsa":[{"id":"GHSA-wf7j-r93f-5cvm","title":"A vulnerability in the Backblaze Client allows a local user to make the system not bootable by...","description":"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.","status":"published","published":"2026-09-01T03:31:03Z","modified":"2026-09-01T18:30:36Z","cvss":[{"version":"4.0","score":7.8,"vector":"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","level":"high"}],"cwes":["CWE-59"],"updated_at":"2026-11-02T15:11:13.913584Z"}],"nvd":[{"id":"CVE-2026-19820","description":"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.","status":"published","published":"2026-09-01T01:16:33.137Z","modified":"2026-09-11T00:17:28.53Z","cvss":[{"version":"4.0","score":7.8,"vector":"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","level":"high","assessor":"secondary"}],"cwes":["CWE-59"],"updated_at":"2026-11-02T14:12:42.691315Z"}]}}