CVE-2021-39686

Local privilege escalation via Binder credential race

Published Mar 16, 2022 · Updated Aug 4, 2024

Race condition in the Linux Kernel Android Binder driver allows local users to escalate privileges through incorrect SELinux security checks. binder.c passes a binder_proc task_struct to SELinux, whose later task-to-SID conversion can race with credential changes and select the wrong security context. Exploitation requires local code execution and a kernel built with the Binder driver, but no user interaction or additional execution privileges.

CVSS severityUnavailable
Unscored
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in the Linux Kernel Android Binder driver allows local users to escalate privileges through incorrect SELinux security checks. binder.c passes a binder_proc task_struct to SELinux, whose later task-to-SID conversion can race with credential changes and select the wrong security context. Exploitation requires local code execution and a kernel built with the Binder driver, but no user interaction or additional execution privileges.

The record

CVE
CVE-2021-39686
Published
Mar 16, 2022
Updated
Aug 4, 2024
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-362, T1068
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Mar 16, 2022CVE 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?

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  1. Affected versionversion=Android kernel

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linux Kernelversion=Android kernel

Published CVSS scores

No CVSS assessment is available in this record.

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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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