dbcve.org
AndroidOperating system · Google

CVE-2021-39712

MEDIUM · 6.4 CVSS v3.1 Published 2022-03-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
66/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In TBD of TBD, there is a possible user after free vulnerability due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-176918884References: N/A

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A user-after-free (UAF) vulnerability exists in the Android kernel due to a race condition. This allows a local attacker with System-level execution privileges to escalate privileges to root without user interaction. The vulnerability stems from improper synchronization when accessing kernel objects, leading to use-after-free scenarios.

MitigationApply the Android kernel security patch for CVE-2021-39712. Ensure Android devices receive regular security updates. For enterprises, implement kernel-level integrity monitoring and restrict System-level access to trusted applications only.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
AndroidOperating system
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
High
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the Android kernel version
    Run 'cat /proc/version' in a terminal app or check Settings > About Phone > Kernel Version
    Affected if The kernel version is older than the patched version for CVE-2021-39712 (patched in Android kernel 4.14, 4.19, 5.4, and 5.10/5.15 depending on branch)
  2. Check the Android Security Patch Level
    Go to Settings > About Phone > Android version > Security patch level, or run 'getprop ro.build.version.security_patch'
    Affected if The Security Patch Level is earlier than the month the CVE was fixed (typically February 2022 or later for Pixel devices)
  3. Verify System-level execution access
    Review installed applications with System-level or root privileges using 'ls -la /system/app/' and check for suspicious or untrusted system apps
    Affected if Untrusted or malicious applications have System-level execution privileges, which is required for exploitation
  4. Check for root access vulnerabilities
    Verify if the device has been rooted or has apps with root access using 'su -c id' or checking for Superuser apps
    Affected if The device has root access vulnerabilities or unauthorized root-privileged apps that could be combined with this UAF for privilege escalation

A device is likely affected if it runs an unpatched Android kernel version and has System-level or root-privileged applications present, as the UAF race condition requires System execution privileges to trigger.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Android kernel security patch for CVE-2021-39712. Ensure Android devices receive regular security updates. For enterprises, implement kernel-level integrity monitoring and restrict System-level access to trusted applications only.

Recommended fix Moderate confidence

Android security patch level 2022-01-05 or later (January 2022 Android Security Bulletin)

  1. 1. Apply the Android security update released in January 2022 or later, which contains the fix for CVE-2021-39712
  2. 2. Verify the device has received the security patch level of 2022-01-05 or later
  3. 3. On supported devices, ensure the latest system and Google Play system updates are installed
  4. 4. If the device is no longer receiving official security updates, consider migrating to a supported device model that receives regular monthly security patches
Caveat Devices approaching end-of-life may not receive this update; some older devices may stop receiving monthly security patches entirely

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Android Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing10.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,580
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-39712 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data