CVE-2018-21131

Unauthenticated firmware downgrade

Published Apr 23, 2020 · Updated Aug 5, 2024

Firmware downgrade in NETGEAR WAC505 and WAC510 before 5.0.0.17 allows remote attackers to install an older firmware image. NETGEAR has not published the affected update locus or the validation failure that accepts a downgrade image. Exploitation requires adjacent-network access without authentication; success replaces the installed firmware with an older release.

CVSS severity8.1
High
EPSS probability1.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Firmware downgrade in NETGEAR WAC505 and WAC510 before 5.0.0.17 allows remote attackers to install an older firmware image. NETGEAR has not published the affected update locus or the validation failure that accepts a downgrade image. Exploitation requires adjacent-network access without authentication; success replaces the installed firmware with an older release.

The record

CVE
CVE-2018-21131
Published
Apr 23, 2020
Updated
Aug 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1601.002
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 23, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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 vectoradjacent
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.1NETGEARCVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
6.4NVDAV:N/AC:L/Au:N/C:N/I:P/A:P
9.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1601.002Downgrade System Image

Public exploit references

No public exploit references are available in this record.

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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