CVE-2021-44527

Adjacent-network service interruption

Published Dec 7, 2021 · Updated Aug 4, 2024

Denial of service in Ubiquiti UniFi Switch firmware 5.64.8 and earlier allows adjacent-network attackers to interrupt the switch. Ubiquiti has not disclosed the affected firmware component, crafted traffic, or resource-consuming operation. Network access is sufficient without authentication or user interaction, and successful exploitation makes the switch unavailable.

CVSS severity6.5
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Ubiquiti UniFi Switch firmware 5.64.8 and earlier allows adjacent-network attackers to interrupt the switch. Ubiquiti has not disclosed the affected firmware component, crafted traffic, or resource-consuming operation. Network access is sufficient without authentication or user interaction, and successful exploitation makes the switch unavailable.

The record

CVE
CVE-2021-44527
Published
Dec 7, 2021
Updated
Aug 4, 2024
Vendor
Ubiquiti Inc.
Product
UniFi Switches
Classifications
CWE-400, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 7, 2021CVE 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Fixed in 5.76.6

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Ubiquiti Inc. · UniFi Switchesversion=Fixed in 5.76.6

Published CVSS scores

6.5UbiquitiCVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.5NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.1NIST NVDAV:A/AC:L/Au:N/C:N/I:N/A:C

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

CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

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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