dbcve.org
AndroidOperating system · Google

CVE-2021-39761

MEDIUM · 5.5 CVSS v3.1 Published 2022-03-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
57/100
Remediation priority · Elevated
Zero-click

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 · unedited
In Media, 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-179783181

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 confidence

A side-channel information disclosure vulnerability in Android's Media component allows any app to determine whether other apps are installed on the device without requiring the query permissions that should normally be enforced. This privacy violation occurs because the Media subsystem leaks information about app presence through observable side effects.

MitigationApply the Android-12L security update (or later) to affected devices. Organizations should inventory their Android device fleet and ensure all devices receive the February 2022 or later security patch 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
AndroidOperating system
Affected:= 12.1

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Check Android version is 12.1
    Go to Settings > About Phone > Android version, or run 'getprop ro.build.version.release' in ADB shell
    Affected if Android version displays exactly 12.1 (not 12, 12.0, 12L, 12.2, or later)
  2. Verify February 2022 security patch not applied
    Go to Settings > About Phone > Security patch level, or run 'getprop ro.build.version.security_patch' in ADB shell
    Affected if Security patch level is earlier than 2022-02-05 (the patch that fixed this issue)
  3. Confirm Media component accessible to apps
    This is the default state in Android 12.1 - no configuration change needed. The vulnerability exists in the Media subsystem's side-channel behavior.
    Affected if Any third-party app can query Media content resolvers and observe side effects that reveal installed app information

Device is affected if running Android version 12.1 with a security patch level earlier than February 2022, as the Media component will leak information about installed apps to any requesting application without proper permission enforcement.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Android-12L security update (or later) to affected devices. Organizations should inventory their Android device fleet and ensure all devices receive the February 2022 or later security patch level.

Recommended fix High confidence

Android 13 (API level 33) or later with January 2022 or later security patch

  1. Check your current Android version by going to Settings > About Phone > Version
  2. Ensure your device is running Android 12L (API level 32) or Android 13 (API level 33) with the latest security patch
  3. Go to Settings > Security > Security update to verify you have the latest security patch installed
  4. If updates are available, download and install them
  5. For devices that cannot receive updates, consider upgrading to a device with longer security update support
Caveat Major Android version upgrades may cause app compatibility issues; backup data before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Android Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing3.0 h
  • Review / QA2.0 h
17.0 hours of engineering $3,050
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-39761 in production — separate from our analysis above.

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What this is

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.

What belongs here
  • 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
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