CVE-2021-30937Public exploit

Kernel code execution via multicast membership race

Published Aug 24, 2021 · Updated Aug 3, 2024

Kernel memory corruption in Apple iOS, iPadOS, macOS, and watchOS allows local users to execute code with kernel privileges. In XNU's IPv4 and IPv6 multicast membership paths, inp_join_group releases locks while retaining an imo_mfilters pointer that a racing membership update can reallocate, then writes through the dangling pointer. A malicious local application must win the race; successful exploitation corrupts kernel heap memory and elevates its code to kernel privilege.

CVSS severity7.8
High
EPSS probability17.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Kernel memory corruption in Apple iOS, iPadOS, macOS, and watchOS allows local users to execute code with kernel privileges. In XNU's IPv4 and IPv6 multicast membership paths, inp_join_group releases locks while retaining an imo_mfilters pointer that a racing membership update can reallocate, then writes through the dangling pointer. A malicious local application must win the race; successful exploitation corrupts kernel heap memory and elevates its code to kernel privilege.

The record

CVE
CVE-2021-30937
Published
Aug 24, 2021
Updated
Aug 3, 2024
Vendor
Apple
Product
iOS and iPadOS
Classifications
CWE-787, T1068
Attack vector
local
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 <15.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Apple · iOS and iPadOSversion=unspecified <15.2
Apple · macOSversion=unspecified <11.6; version=unspecified <12.1; version=unspecified <15.2; version=unspecified <2021
Apple · watchOSversion=unspecified <8.3

Published CVSS scores

9.3NIST NVDAV:N/AC:M/Au:N/C:C/I:C/A:C
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1068Exploitation for Privilege Escalation

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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