CVE-2021-39778
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 Telecomm, there is a possible way to determine whether an app is installed, without query permissions, due to improper input validation. 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-196406138
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 Telecomm component (Android-12L), improper input validation allows a local attacker to determine whether specific applications are installed on the device without possessing the required query permissions. This information disclosure occurs without any user interaction and requires no 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= 12.0CVSS 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
- 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 12.0 (Android-12L)
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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 update containing the CVE-2021-39778 fix
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Verify Telecomm component presenceCheck for presence of TelecomService or Telecomm service on the device. Run 'dumpsys telecom' via ADB shell to confirm the component is accessibleAffected if Telecomm component is present and responding (standard on Android devices with telephony)
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Confirm no third-party security Apps are blocking the vulnerable componentReview if any mobile security or MDM solutions are actively monitoring or blocking app enumeration queries to the Telecomm serviceAffected if No security solution is intercepting these queries
A device is affected if it runs Android 12.0 and has a security patch level earlier than the Android-12L update containing the CVE-2021-39778 fix, with the Telecomm component active and unmitigated by external security controls.
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-2021-39778 (part of the Android-12L security update) which contains the fix for the improper input validation in the Telecomm component.
Android 12L with January 2022 security patch or later; Android 13 stable release
- Upgrade the device to Android 12L with the latest security patch update
- Alternatively, upgrade to Android 13 which contains the security fix for this vulnerability
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 h
- Testing5.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,752.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39778 — 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-2021-39778 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