Quick answers
- Is CVE-2026-19820 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-19820 being exploited in the wild.
- How severe is CVE-2026-19820?
- Informational severity, published 1 September 2026.
- Which products and versions are affected?
- Backblaze Client <UNKNOWN>.
- Is there a fix for CVE-2026-19820?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-19820 attacked?
- It is attacked with local access.
- Am I affected by CVE-2026-19820?
- Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is an improper link resolution flaw in Backblaze Client's backup engine. A local administrator can create a symbolic link from Backblaze's backup folder to Windows system directories; when the backup process follows the link without proper validation, it overwrites critical OS files required for boot. The attack vector is local, requires administrator privileges, and also requires that the target system has administrative-level security controls disabled (such as reparse point restrictions). Successful exploitation renders the system unbootable. Patch availability is not specified in available sources.
Affected products
- Backblaze Client <UNKNOWN>
Timeline
- 2026-09-01: disclosed