CVE-2021-39774
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 Bluetooth, there is a possible out of bounds read due to a missing bounds check. This could lead to local denial of service with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12LAndroid ID: A-205989472
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 confidenceIn Android's Bluetooth stack, a missing bounds check allows an out-of-bounds read vulnerability. This could be exploited locally to cause a denial of service condition without requiring elevated privileges or user interaction. The vulnerability exists in Android-12L Bluetooth component.
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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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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Identify Android OS versionGo to Settings > About Phone > Android version, or run 'getprop ro.build.version.release' via ADB shellAffected if The Android version is exactly 12.0 (Android-12L)
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Confirm Bluetooth is enabledCheck if Bluetooth is turned on in Settings > Bluetooth, or run 'settings get global bluetooth_on' via ADBAffected if Bluetooth is enabled on the device (the vulnerable component is active)
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Verify Android 12L buildCheck the build fingerprint or security patch level via 'getprop ro.build.version.incremental' or 'getprop ro.build.version.security_patch' via ADBAffected if Build shows Android-12L (S2B2.211027.006 or similar 12L builds) with no security patch applied
If the device runs Android 12.0 and has Bluetooth enabled, it is vulnerable to the out-of-bounds read in the Bluetooth component.
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 security patch for CVE-2021-39774 (Android-12L). For enterprise deployments, ensure devices receive monthly security updates and consider Bluetooth usage policies as a defense-in-depth measure until patches are applied.
Android December 2021 Security Patch Level (SMR Dec-2021) or later
- Check your Android device's current security patch level in Settings > About Phone > Security Patch Level
- If the device is on Android 12 or 12L and has a security patch level earlier than December 2021, check for a system software update
- Apply the December 2021 Android Security Update or later via Settings > System > Software Update > Check for Updates
- 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.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39774 — 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-2021-39774 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