CVE-2020-8289

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 4.7% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2020-12-27 · updated 2026-06-17
Weakness: CWE-295

Description

Backblaze for Windows before 7.0.1.433 and Backblaze for macOS before 7.0.1.434 suffer from improper certificate validation in `bztransmit` helper due to hardcoded whitelist of strings in URLs where validation is disabled leading to possible remote code execution via client update functionality.

Affected products

Backblaze: before 7.0.1.433; before 7.0.1.434 — fixed in 7.0.1.433, 7.0.1.434

How to fix

Upgrade to a fixed version: Backblaze 7.0.1.433, 7.0.1.434. Check the vendor advisory for mitigations.

References

http://seclists.org/fulldisclosure/2020/Dec/57
http://seclists.org/fulldisclosure/2020/Dec/58
https://github.com/geffner/CVE-2020-8289/blob/master/README.md
https://hackerone.com/reports/818853
https://www.backblaze.com/blog/backblaze-cloud-backup-release-7-0-1/
https://youtu.be/W0THXbcX5V8
http://seclists.org/fulldisclosure/2020/Dec/57
http://seclists.org/fulldisclosure/2020/Dec/58
https://github.com/geffner/CVE-2020-8289/blob/master/README.md
https://hackerone.com/reports/818853
https://www.backblaze.com/blog/backblaze-cloud-backup-release-7-0-1/
https://youtu.be/W0THXbcX5V8

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