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Fencer Vulns
high 7.8

CVE-2020-8289 json

Backblaze for Windows before 7.0.1.433 and Backblaze for macOS before 7.0.1.434 suffer from improper certificate validation in `bztransmit`…

published 2020-12-27 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-29157

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.7%
EPSS 4.7% chance of exploitation in 30 days, percentile 91%
public exploits
0
none known

Summary

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.

Patch / fix

  • backblaze backblaze 7.0.1.433, 7.0.1.434

Exploit prediction

4.70% chance of exploitation in the next 30 days, higher than 91% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • youtu.be https://youtu.be/W0THXbcX5V8 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/geffner/CVE-2020-8289/blob/master/README.md referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 9.3 AV:N/AC:M/Au:N/C:C/I:C/A:C

Affected products

  • n/a Backblaze

Classification

Weakness
  • CWE-295 Improper Certificate Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.