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Fencer Vulns
critical 9.8

CVE-2021-36226 json

Western Digital My Cloud devices before OS5 do not use cryptographically signed Firmware upgrade files.

published 2023-02-06 3 y ago modified 2026-06-17 4 mo ago also EUVD-2021-22846

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

Western Digital My Cloud devices before OS5 do not use cryptographically signed Firmware upgrade files.

Patch / fix

  • westerndigital my_cloud_os 5.02.104

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
19 mo ago

Exploit prediction

0.81% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • krebsonsecurity.com https://krebsonsecurity.com/2021/07/another-0-day-looms-for-many-western-digital-users/ referenced PoC, tagged "exploit" by a source, unverified
  • youtube.com https://www.youtube.com/watch?v=vsg9YgvGBec referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/pedrib/PoC/blob/master/advisories/Pwn2Own/Tokyo_2020/weekend_destroyer/weekend_destroyer.md referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Classification

Weakness
  • CWE-347 Improper Verification of Cryptographic Signature

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.