CVE-2021-39776
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 NFC, there is a possible memory corruption due to a use after free. This could lead to local escalation of privilege with User execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12LAndroid ID: A-192614125
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 confidenceA use-after-free vulnerability in the Android NFC subsystem allows a local attacker with user execution privileges to corrupt memory and escalate privileges. The vulnerability stems from the NFC component improperly handling memory that has been freed, potentially allowing an attacker to manipulate memory state and execute arbitrary code at a higher privilege level.
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= 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
- 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 checksWork through these to decide whether this CVE applies to you.
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Verify the Android version is 12.0Go to Settings > About Phone > Android version, or run 'getprop ro.build.version.release' via ADB shellAffected if The version shown is exactly 12.0 (not 12.0 with additional sub-version numbers, not 12L, not 13, etc.)
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Confirm NFC is enabled on the deviceNavigate to Settings > Network & Internet > NFC, or check via ADB with 'settings get secure nfc_enabled'Affected if NFC is turned ON - the vulnerability exists in the NFC component so it only applies when NFC is active
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Check the security patch levelGo to Settings > About Phone > Security patch level, or run 'getprop ro.build.version.security_patch' via ADB shellAffected if The patch level is earlier than 2022-02; versions 2022-02 or later contain the fix for this CVE
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Check the build fingerprint for update statusRun 'getprop ro.build.fingerprint' via ADB shell and look for 'Android-12L' or later identifiers in the build stringAffected if The build does not indicate Android-12L (S2B2.220217.004 or later) or a 2022-02 security update is not present
A device is affected only if it runs Android 12.0 exactly, has NFC enabled, and has a security patch level earlier than February 2022 (2022-02).
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 the Android-12L security update (patch level 2022-02 or later) which contains the fix for this NFC use-after-free vulnerability. Organizations should ensure mobile devices receive regular security patches.
Android 12L with December 2021 security patch level (2021-12-01) or later
- Ensure your Android device is running Android 12L (API level 32)
- Check for and install the latest system updates via Settings > System > Software Update
- Verify the security patch level is December 2021 (2021-12-01) or later under Settings > About Phone > Android version
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39776 — 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-2021-39776 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