CVE-2021-39766
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 Settings, there is a possible way to determine whether an app is installed, without query permissions, due to side channel information disclosure. This could lead to local information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12LAndroid ID: A-198296421
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 side-channel information disclosure vulnerability in Android Settings allows a local attacker to determine whether specific applications are installed on the device without requiring query permissions. This privacy leak enables malicious apps to enumerate installed software without any user interaction or elevated 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= 12.1CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Check Android versionGo to Settings > About Phone > Android version or run 'getprop ro.build.version.release' in ADB shellAffected if Version shows 12.1 (Android 12L) specifically - this is the only affected version listed
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Verify Settings app versionGo to Settings > Apps > Settings app > Version info, or run 'dumpsys package com.android.settings' in ADB shell to see version detailsAffected if Settings app version corresponds to the unpatched Android 12.1 build
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Check security patch levelGo to Settings > About Phone > Security patch level, or run 'getprop ro.build.version.security_patch' in ADB shellAffected if Patch level is earlier than the Android-12L security update (typically January 2022 or earlier for Android 12.1)
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Test for the side-channel behaviorUse a test app or ADB command 'pm list packages' to enumerate packages - on a vulnerable system, apps like the malicious app described in CVE can enumerate packages without any permission grantsAffected if Other apps can enumerate installed packages without being granted QUERY_ALL_PACKAGES permission
Device is affected if running Android 12.1 (12L) with a security patch level prior to the Android-12L update, allowing any app to enumerate installed packages without explicit permissions.
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.
From vendor dataApply Android-12L security patches from Google. Organizations should enforce MDM policies to restrict sideloaded apps and monitor for suspicious app enumeration behavior.
- Consultation2.0 h
- Testing1.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39766 — 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-2021-39766 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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- 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