CVE-2026-19820 Backblaze Client for Windows Improper Link Resolution Vulnerability
A local attacker can render the system unbootable by exploiting improper link resolution during backup, requiring specific administrative configuration changes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-19820?
CVE-2026-19820 is a medium-severity path traversal vulnerability in Backblaze Client, published on 1 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-59
Which versions are affected by CVE-2026-19820?
How do I fix CVE-2026-19820?
No fix has been published for CVE-2026-19820 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-19820 being exploited?
There is no known exploitation of CVE-2026-19820 in the wild and no public exploit code.
Sources
Also known as GHSA-wf7j-r93f-5cvm.