dbcve.org
AndroidOperating system · Google

CVE-2021-39777

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 Telephony, there is a possible way to determine whether an app is installed, without query permissions, due to a missing permission check. 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-194743207

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

This is a local information disclosure vulnerability in the Android Telephony component. The issue is a missing permission check that allows any app to determine whether other apps are installed on the device without requiring query permissions. This enables app enumeration without elevated privileges.

MitigationThis is a platform-level vulnerability in Android that requires a system update from Google to patch the missing permission check in the Telephony component. Organizations should ensure devices are updated to the latest Android 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:= 12.0

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
    Go to Settings > About Phone > Android version, or run 'getprop ro.build.version.release' via ADB
    Affected if The version is exactly 12.0 (the vulnerability affects this specific version)
  2. Check Android security patch level
    Go to Settings > About Phone > Security patch level, or run 'getprop ro.build.version.security_patch' via ADB
    Affected if The security patch level is earlier than the November 2021 Android Security Bulletin (the patch for this CVE was released in November 2021)
  3. Verify Telephony component is accessible
    The Telephony component (package: com.android.phone) is a system component present by default on all Android devices; no additional configuration check is needed as the vulnerability stems from a missing permission check in this component
    Affected if The Telephony component is present on the device (which is the default state for all Android devices)

The device is affected if it runs Android 12.0 and has a security patch level earlier than November 2021, as the missing permission check vulnerability in the Telephony component allows unauthorized app enumeration.

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

This is a platform-level vulnerability in Android that requires a system update from Google to patch the missing permission check in the Telephony component. Organizations should ensure devices are updated to the latest Android security patch level.

Recommended fix High confidence

Android 13 (API 33) with April 2022 Security Patch Level or later

  1. Check your device manufacturer for the Android 13 (API 33) or later system image that includes the April 2022 security patch (or later)
  2. Navigate to Settings > System > Software Update (or Settings > About Phone > System Update)
  3. Download and install the available system update
  4. Alternatively, if your device supports it, perform a factory reset after backing up data and flash a factory image with the April 2022 security patch level or higher
  5. Verify the patch level by going to Settings > About Phone > Android version and confirming the Security patch level is April 2022 or later
Caveat Upgrading to Android 13 may cause compatibility issues with older apps that do not support the new API level; some device-specific features may change

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

Fix this in Android Scoped from the published advisory
  • Consultation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $880
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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-2021-39777 in production — separate from our analysis above.

No notes yet

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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
  • No spam, self-promotion, credentials, or personal data