CVE-2020-8289

Name: CVE-2020-8289
Creator: NVD / NIST
Published: 2020-12-27T02:15:14.48+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.8/10EPSS 4.66%

Last modified Jun 17, 2026

CVE-2020-8289 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. 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.. EPSS estimates a 4.66% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS Probability

4.66%

90.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Backblaze	Backblaze	< 7.0.1.433
Backblaze	Backblaze	< 7.0.1.434

References

http://seclists.org/fulldisclosure/2020/Dec/57Mailing List, Third Party Advisory
http://seclists.org/fulldisclosure/2020/Dec/58Mailing List, Third Party Advisory
https://github.com/geffner/CVE-2020-8289/blob/master/README.mdExploit, Third Party Advisory
https://hackerone.com/reports/818853Permissions Required
https://www.backblaze.com/blog/backblaze-cloud-backup-release-7-0-1/Third Party Advisory
https://youtu.be/W0THXbcX5V8Exploit, Third Party Advisory
http://seclists.org/fulldisclosure/2020/Dec/57Mailing List, Third Party Advisory
http://seclists.org/fulldisclosure/2020/Dec/58Mailing List, Third Party Advisory
https://github.com/geffner/CVE-2020-8289/blob/master/README.mdExploit, Third Party Advisory
https://hackerone.com/reports/818853Permissions Required
https://www.backblaze.com/blog/backblaze-cloud-backup-release-7-0-1/Third Party Advisory
https://youtu.be/W0THXbcX5V8Exploit, Third Party Advisory

Timeline

Published: Dec 27, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-8289?

How severe is CVE-2020-8289?

CVE-2020-8289 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 4.66% probability of exploitation in the next 30 days.

How do I fix CVE-2020-8289?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-8289?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST