CVE-2021-36224Public exploitNetwork attack vector

Unauthenticated API access via blank system account

Published Feb 6, 2023 · Updated Aug 4, 2024

Authentication bypass in Western Digital PR4100 firmware 2.40.157 and earlier allows remote attackers to access the REST API. Firmware provisions the nobody system account with an empty password, and API authentication accepts the credentials for USER_AUTH endpoints. Default LAN exposure permits low-privilege API actions; full root code execution requires chaining separate firmware-update flaws.

CVSS severity9.8
Critical
EPSS probability1.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Western Digital PR4100 firmware 2.40.157 and earlier allows remote attackers to access the REST API. Firmware provisions the nobody system account with an empty password, and API authentication accepts the credentials for USER_AUTH endpoints. Default LAN exposure permits low-privilege API actions; full root code execution requires chaining separate firmware-update flaws.

The record

CVE
CVE-2021-36224
Published
Feb 6, 2023
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-798, T1078.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 6, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-798Use of Hard-coded Credentials
T1078.001Default Accounts

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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