CVE-2020-9839Known exploitationPublic exploit

Local privilege escalation via state-handling race

Published Jun 9, 2020 · Updated Aug 4, 2024

Race condition in Apple System Preferences allows local users to gain elevated privileges on affected iOS, macOS, tvOS, and watchOS releases. On macOS, cfprefsd fails to lock file-permission operations, allowing CFPreferencesSetAppValue to win a race and overwrite an arbitrary file as root; Apple has not published equivalent implementation detail for the other platforms. Affected releases are iOS before 13.5, macOS before 10.15.5, tvOS before 13.4.5, and watchOS before 6.2.5; exploitation requires low-privileged code execution.

CVSS severity7.0
High
EPSS probability3.67%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Apple System Preferences allows local users to gain elevated privileges on affected iOS, macOS, tvOS, and watchOS releases. On macOS, cfprefsd fails to lock file-permission operations, allowing CFPreferencesSetAppValue to win a race and overwrite an arbitrary file as root; Apple has not published equivalent implementation detail for the other platforms. Affected releases are iOS before 13.5, macOS before 10.15.5, tvOS before 13.4.5, and watchOS before 6.2.5; exploitation requires low-privileged code execution.

The record

CVE
CVE-2020-9839
Published
Jun 9, 2020
Updated
Aug 4, 2024
Vendor
Apple
Product
iOS
Classifications
CWE-362, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 9, 2020CVE 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=unspecified <iOS 13.5 and iPadOS 13.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Apple · iOSversion=unspecified <iOS 13.5 and iPadOS 13.5
Apple · tvOSversion=unspecified <tvOS 13.4.5
Apple · macOSversion=unspecified <macOS Catalina 10.15.5
Apple · watchOSversion=unspecified <watchOS 6.2.5

Published CVSS scores

7.0NIST NVDCVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
5.1NIST NVDAV:N/AC:H/Au:N/C:P/I:P/A:P
7.8Trend Micro Zero Day InitiativeCVSS:3.0/AV:L/AC:L/PR:L/UI:N/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
Privilegesauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

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

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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