CVE-2026-19820
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.
INFO
Published Date :
Sept. 1, 2026, 1:16 a.m.
Last Modified :
Sept. 1, 2026, 1:16 a.m.
Remotely Exploit :
Yes !
Source :
4ac701fe-44e9-4bcd-9585-dd6449257611
Affected Products
The following products are affected by CVE-2026-19820
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | MEDIUM | 4ac701fe-44e9-4bcd-9585-dd6449257611 | ||||
| CVSS 4.0 | HIGH | 4ac701fe-44e9-4bcd-9585-dd6449257611 |
Solution
- Update the Backblaze client software.
- Ensure OS security controls are in place.
- Review file system integrity after updates.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-19820.
| URL | Resource |
|---|---|
| https://www.backblaze.com/computer-backup/docs/backup-client-release-notes-windows | |
| https://www.backblaze.com/status/update |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-19820 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-19820
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-19820 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-19820 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 4ac701fe-44e9-4bcd-9585-dd6449257611
Sep. 01, 2026
Action Type Old Value New Value 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. Added CVSS V4.0 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 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/19xxx/CVE-2026-19820.json">CVE-2026-19820</a> Added Reference https://www.backblaze.com/computer-backup/docs/backup-client-release-notes-windows Added Reference https://www.backblaze.com/status/update