CVE-2021-39756
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 Framework, 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-184354287
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 Framework allows local attackers to determine whether an app is installed without requiring QUERY_ALL_PACKAGES permission. The vulnerability leaks presence information through a timing or other observable side channel, enabling privacy-invasive app enumeration without any special 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' via ADB shellAffected if Version equals 12.1 (the specific affected version listed)
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Check security patch levelGo to Settings > About Phone > Security patch level or run 'getprop ro.build.version.security_patch' via ADB shellAffected if Patch level is earlier than the Android-12L security patch that addresses this issue
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Verify no QUERY_ALL_PACKAGES permission is granted to suspicious appsRun 'dumpsys package permissions' or review app permissions in Settings to see which apps hold QUERY_ALL_PACKAGESAffected if An app without QUERY_ALL_PACKAGES can enumerate other installed apps (indicating the vulnerability may be present)
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Test for timing-based app enumerationAttempt to measure response time when querying package manager for non-existent vs existing app package names repeatedlyAffected if Noticeable timing differences reveal the side channel is present and exploitable
A device is affected if it runs Android version 12.1 and has not received the Android-12L security patch that mitigates this framework side channel.
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 patch (or later) when released by Google/AOSP. No application-level remediation is possible as this is an OS framework vulnerability.
Android 13 (or any later stable release)
- Upgrade the device to Android 13 or later, which contains the fix for this Framework side-channel information disclosure vulnerability
- Verify the upgrade by checking Settings > About Phone > Android version confirms Android 13 or higher
- Ensure monthly security patches are applied after upgrade to maintain protection against other vulnerabilities
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Testing8.0 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 $3,712.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39756 — 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-2021-39756 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