CVE-2021-36225Public exploitNetwork attack vector

Low-privileged firmware installation via USER_AUTH endpoint

Published Feb 6, 2023 · Updated Mar 26, 2025

Missing authorization in Western Digital PR4100 firmware 2.40.157 and earlier allows remote authenticated users to install firmware. The /api/2.1/rest/firmware_update POST handler accepts an upload, passes the file path to manualFWUpdate(), and invokes the privileged firmware installer. A low-privileged REST account can trigger a firmware flash and reboot, while arbitrary code execution depends on a separate firmware-verification flaw.

CVSS severity8.8
High
EPSS probability1.05%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authorization in Western Digital PR4100 firmware 2.40.157 and earlier allows remote authenticated users to install firmware. The /api/2.1/rest/firmware_update POST handler accepts an upload, passes the file path to manualFWUpdate(), and invokes the privileged firmware installer. A low-privileged REST account can trigger a firmware flash and reboot, while arbitrary code execution depends on a separate firmware-verification flaw.

The record

CVE
CVE-2021-36225
Published
Feb 6, 2023
Updated
Mar 26, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-862, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 6, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 26, 2025Record 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 privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-862Missing Authorization
T1190Exploit Public-Facing Application

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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