CVE-2021-39629
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 · uneditedIn phTmlNfc_Init and phTmlNfc_CleanUp of phTmlNfc.cc, there is a possible use after free due to a race condition. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-10 Android-11 Android-12 Android-9Android ID: A-197353344
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 confidenceUse-after-free vulnerability in Android NFC subsystem (phTmlNfc.cc) in the phTmlNfc_Init and phTmlNfc_CleanUp functions. A race condition allows memory to be freed while still being accessed, leading to local privilege escalation without user interaction or additional execution privileges.
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= 9.0= 10.0= 11.0= 12.0CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:H/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 checksWork through these to decide whether this CVE applies to you.
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Confirm device is running AndroidCheck the operating system by reviewing system properties or settings - look for Android OS identifierAffected if Device is not running Android (this CVE affects only Android)
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Identify Android versionRun 'getprop ro.build.version.release' or check Settings > About Phone > Android versionAffected if Version is 9.0, 10.0, 11.0, or 12.0 exactly (these are the affected versions)
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Verify NFC subsystem is presentCheck for NFC hardware and service - look for 'nfc' in getprop output or check Settings > Connected devices > NFCAffected if NFC hardware and NFC Android service are present on the device
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Confirm NFC is enabledCheck NFC status via Settings or by running 'settings get secure nfc_on'Affected if NFC is turned on (the vulnerable code in phTmlNfc.cc executes when NFC is active)
Device is affected if it runs Android 9.0, 10.0, 11.0, or 12.0 with NFC hardware present and enabled, as the use-after-free vulnerability exists in the phTmlNfc_Init and phTmlNfc_CleanUp functions of the NFC subsystem.
Generated from the published advisory. Verify against your own configuration.
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 · scopedApply Android monthly security update (December 2021 or later) which contains the patch for this vulnerability. No user interaction required for exploitation, so prioritize patching fleet devices.
Android devices with December 2021 Security Patch Level (SPL) or later
- 1. Check current Android security patch level on the device: Settings > About Phone > Security Patch Level
- 2. If the Security Patch Level is earlier than December 2021, check for system updates: Settings > System > System Update
- 3. Download and install the latest available system update that includes the December 2021 Android Security Bulletin patches
- 4. Verify the Security Patch Level has been updated to December 2021 or later after the update completes
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,936.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39629 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-39629 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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