CVE-2021-30868

Kernel code execution via SMB race condition

Published Aug 24, 2021 · Updated Aug 3, 2024

A race condition in Apple macOS SMB allows local users to execute kernel code on Big Sur before 11.6.1 and Monterey before 12.0.1. The SMB implementation fails to lock an undisclosed shared resource against concurrent operations controlled by a malicious application. Exploitation requires local application execution and winning the timing window, after which code runs with kernel privileges.

CVSS severity7.0
High
EPSS probability0.74%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A race condition in Apple macOS SMB allows local users to execute kernel code on Big Sur before 11.6.1 and Monterey before 12.0.1. The SMB implementation fails to lock an undisclosed shared resource against concurrent operations controlled by a malicious application. Exploitation requires local application execution and winning the timing window, after which code runs with kernel privileges.

The record

CVE
CVE-2021-30868
Published
Aug 24, 2021
Updated
Aug 3, 2024
Vendor
Apple
Product
macOS
Classifications
CWE-362, CAPEC-26, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=unspecified <11.6
  2. Affected versionversion=unspecified <12.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Apple · macOSversion=unspecified <11.6; version=unspecified <12.0

Published CVSS scores

7.6NIST NVDAV:N/AC:H/Au:N/C:C/I:C/A:C
7.0NIST NVDCVSS:3.1/AV:L/AC:H/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.

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CAPEC-26Leveraging Race Conditions
T1068Exploitation for Privilege Escalation

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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