Backblaze Client for Windows Improper Link Resolution Vulnerability
Priority LOW 33CWE-59Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · None
- Fix status
- No fix listed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0049 42nd percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2026-19820
- 2026-10-03 Alias added: GHSA-wf7j-r93f-5cvm
References
More Backblaze vulnerabilities
- TI-2020-06706 Improper certificate validation in Backblaze CVSS 3.1HIGH 7.8
- TI-2020-06707 Improper privilege management in Backblaze CVSS 3.1HIGH 7.8
- TI-2022-07705 B2 Command Line Tool TOCTOU application key disclosure CVSS 3.1MEDIUM 4.7
- TI-2022-07703 b2-sdk-python TOCTOU application key disclosure CVSS 3.1MEDIUM 4.7
Sources
- CVE-2026-19820 · CVE Program
- CVE-2026-19820 · NVD
- FIRST EPSS
- GHSA-wf7j-r93f-5cvm · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences