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AndroidOperating system · Google

CVE-2021-39700

MEDIUM · 5.5 CVSS v3.1 Published 2022-05-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
57/100
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 the policies of adbd.te, there was a logic error which caused the CTS Listening Ports Test to report invalid results. This could lead to local information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-10 Android-11 Android-12Android ID: A-201645790

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 logic error in the SELinux policy file (adbd.te) for the Android Debug Bridge daemon (adbd) causes the CTS Listening Ports Test to report invalid results. This policy misconfiguration allows local information disclosure without requiring additional execution privileges or user interaction.

MitigationApply the Android security patch that corrects the adbd.te SELinux policy logic. This is typically delivered through monthly platform security updates for Android 10, 11, and 12.

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:= 10.0= 11.0= 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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

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

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. Check Android version
    Run 'getprop ro.build.version.release' in ADB shell or check Settings > About Phone > Android version
    Affected if The version is 10.0, 11.0, or 12.0 AND the security patch level is older than the fix release date (typically December 2021 or later)
  2. Check security patch level
    Run 'getprop ro.build.version.security_patch' in ADB shell
    Affected if The patch level date is earlier than when the fix was delivered (patch dates vary by carrier/device, generally December 2021 or later)
  3. Verify SELinux policy state for adbd
    If root access is available, inspect the SELinux policy using 'sesearch --allow -s adbd -t shell_data_file -c dir' or similar adbd-related policy queries; otherwise, run the CTS test specified in the CVE
    Affected if The CTS Listening Ports Test reports invalid results, indicating the adbd.te policy misconfiguration is present

A device is affected if it runs Android 10, 11, or 12 with a security patch level predating the fix and the CTS Listening Ports Test fails, confirming the adbd SELinux policy misconfiguration allows unauthorized local information disclosure.

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 that corrects the adbd.te SELinux policy logic. This is typically delivered through monthly platform security updates for Android 10, 11, and 12.

Recommended fix High confidence

Android 12 with December 2021 security patch or later; for Android 10/11 devices, update to the latest available security patch for that Android version

  1. Ensure the device is connected to a network and check for system updates in Settings > System > System Update
  2. Install the latest Android security patch update for your device
  3. After updating, verify the SELinux policy has been updated by checking that the adbd.te policy no longer contains the logic error - this is typically automatic with the security patch
  4. For devices that no longer receive official updates, consider migrating to a custom ROM with newer SELinux policies or replacing the device
Caveat Standard system update - ensure user data is backed up before applying major updates; some older apps may have compatibility issues with newer Android versions

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

Fix this in Android Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,920
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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-2021-39700 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