CVE-2021-30866

Device tracking via broadcast Wi-Fi MAC address

Published Aug 24, 2021 · Updated Aug 3, 2024

Information disclosure in bootp before iOS 15, iPadOS 15, tvOS 15, and watchOS 8 allows physically proximate attackers to track devices. The component broadcasts the hardware MAC address in Wi-Fi traffic rather than suppressing it, creating a stable identifier that passive observers can correlate across time and locations. Exploitation requires wireless proximity and passive traffic observation; Apple reports tracking exposure, not data modification or service interruption.

CVSS severity6.5
Medium
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in bootp before iOS 15, iPadOS 15, tvOS 15, and watchOS 8 allows physically proximate attackers to track devices. The component broadcasts the hardware MAC address in Wi-Fi traffic rather than suppressing it, creating a stable identifier that passive observers can correlate across time and locations. Exploitation requires wireless proximity and passive traffic observation; Apple reports tracking exposure, not data modification or service interruption.

The record

CVE
CVE-2021-30866
Published
Aug 24, 2021
Updated
Aug 3, 2024
Vendor
Apple
Product
iOS and iPadOS
Classifications
T1040
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 24, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=unspecified <15

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Apple · iOS and iPadOSversion=unspecified <15
Apple · tvOSversion=unspecified <15
Apple · watchOSversion=unspecified <8

Published CVSS scores

3.3NIST NVDAV:A/AC:L/Au:N/C:P/I:N/A:N
6.5NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1040Network Sniffing

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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