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AndroidOperating system · Google

CVE-2021-39810

HIGH · 7.8 CVSS v3.1 Published 2023-10-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
Remediation priority · High
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 verifyDefaults of CardEmulationManager.java, there is a possible way to set a third party app as the default contactless payment app without user consent 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.

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

A missing permission check in the verifyDefaults method of CardEmulationManager.java allows a malicious local application to set itself as the default contactless payment app without user consent, achieving local privilege escalation. The vulnerability exists in Android's NFC card emulation functionality used for mobile payments.

MitigationApply the vendor-specific Android security patch for CVE-2021-39810 which adds proper permission verification in the CardEmulationManager.verifyDefaults method. Users should update their devices promptly when patches become available.

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:= 13.0

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
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/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. Check Android version is 13.0
    Go to Settings > About Phone > Android version, or run 'getprop ro.build.version.release' via ADB shell
    Affected if Android version equals 13.0 exactly (the only affected version listed)
  2. Verify NFC is enabled
    Go to Settings > Network & Internet > NFC, or check via ADB: 'settings get secure nfc_enabled'
    Affected if NFC is turned on - the attack surface only exists when NFC is enabled
  3. Check if NFC payment/default payment app is set
    Go to Settings > Apps > Default apps > Tap payment, or inspect 'content query --uri content://nfc/settings --projection default_payment_service'
    Affected if A default contactless payment app is configured - the vulnerability allows unauthorized changes to this setting
  4. Review installed apps with payment or card emulation permissions
    Check installed apps via ADB: 'dumpsys package | grep -i payment' or inspect app permissions for HCE/NFC-related capabilities
    Affected if Any app has been set as the default payment app without user intent - indicates potential exploitation

You are affected only if running Android 13.0 with NFC enabled and NFC payment functionality in use; the vulnerability allows any local app to intercept the default payment app setting without user consent when these conditions are met.

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 vendor-specific Android security patch for CVE-2021-39810 which adds proper permission verification in the CardEmulationManager.verifyDefaults method. Users should update their devices promptly when patches become available.

Recommended fix Moderate confidence

Latest Android security patch level (2021-10-01 or later) / Android 14+

  1. 1. Check the current Android security patch level on the device (Settings > About Phone > Security Patch Level)
  2. 2. Apply the latest available Android security update for your device
  3. 3. If Android 13.0 is still in use, upgrade to the latest stable Android release (Android 14 or later)
  4. 4. Verify the upgrade was successful by confirming the security patch level is current
Caveat Newer Android versions may have UI changes and may drop support for older apps

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-2021-39810 in production — separate from our analysis above.

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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