CVE-2026-19820

Backblaze Client for Windows Improper Link Resolution Vulnerability

Published Sep 1, 2026 CVSS 4.0 · 5.8 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Weaknesses CWE-20
CWE-269
CWE-272
Type Values Removed Values Added
Weaknesses CWE-59
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Backblaze
Backblaze backblaze
Vendors & Products Backblaze
Backblaze backblaze
Type Values Removed Values Added
Weaknesses CWE-20
CWE-269
CWE-272
Type Values Removed Values Added
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.
Title Backblaze Client for Windows Improper Link Resolution Vulnerability
References
Metrics cvssV4_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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Bugcrowd
Published
Updated
Sep 10, 2026, 11:32 PM
Reserved
Aug 14, 2026, 5:28 AM
Status
Deferred
Published
Sep 1, 2026, 1:16 AM
Modified
Sep 11, 2026, 12:17 AM