dbcve.org
AndroidOperating system · Google

CVE-2021-39772

HIGH · 8.8 CVSS v3.1 Published 2022-03-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
93/100
Remediation priority · Urgent
No privileges 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 Bluetooth, there is a possible way to access the a2dp audio control switch due to a missing permission check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12LAndroid ID: A-181962322

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 · high confidence

This is a missing permission check vulnerability in Android's Bluetooth stack that allows unauthorized access to the a2dp (Advanced Audio Distribution Profile) audio control switch. The flaw enables local privilege escalation without requiring additional execution privileges or user interaction, specifically affecting Android-12L.

MitigationApply the Android security patch for Android-12L that addresses the missing permission check in the Bluetooth a2dp audio control functionality. Organizations should ensure devices receive the latest Google monthly security updates.

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:= 12.0

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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/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 Android version
    Navigate to Settings > About Phone > Android version, or run the command 'adb shell getprop ro.build.version.release'
    Affected if The reported Android version is 12.0 (Android-12L)
  2. Confirm Bluetooth is enabled
    Navigate to Settings > Bluetooth and verify it is turned on, or run 'adb shell settings get global bluetooth_on' to check if Bluetooth is active
    Affected if Bluetooth is enabled on a device running Android 12.0
  3. Verify A2DP profile support
    Check if the device supports Bluetooth audio streaming by reviewing Bluetooth settings or running 'adb shell dumpsys bluetooth_manager' to list supported profiles
    Affected if The device supports the A2DP (Advanced Audio Distribution Profile) and is running Android 12.0
  4. Check security patch level
    Navigate to Settings > About Phone > Security patch level, or run 'adb shell getprop ro.build.version.security_patch'
    Affected if The security patch level is earlier than the Android 12L security update that addresses CVE-2021-39772

A device is affected if it is running Android 12.0 with Bluetooth enabled, supports the A2DP profile, and has a security patch level predating the fix for the missing permission check vulnerability in the Bluetooth a2dp audio control functionality.

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 security patch for Android-12L that addresses the missing permission check in the Bluetooth a2dp audio control functionality. Organizations should ensure devices receive the latest Google monthly security updates.

Recommended fix High confidence

Android 13 or Android 12L with January 2022 security patch

  1. Check current Android version by navigating to Settings > About Phone > Android version
  2. Check current security patch level by going to Settings > About Phone > Security patch level
  3. If running Android 12 or 12L, upgrade to Android 13 or later which contains the fix for this vulnerability
  4. Alternatively, ensure the device has the January 2022 security patch level installed via Settings > Security > Security update
  5. After updating, verify the Bluetooth permission model has been corrected by attempting to access a2dp audio controls (should now require appropriate permissions)
Caveat Android 13 may have UI changes and deprecated APIs compared to Android 12; verify app compatibility before deploying enterprise-wide

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

Fix this in Android Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,560
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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-2021-39772 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