CVE-2021-0538
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 onCreate of EmergencyCallbackModeExitDialog.java, there is a possible exit of emergency callback mode due to a tapjacking/overlay attack. This could lead to local escalation of privilege with User execution privileges needed. User interaction is needed for exploitation.Product: AndroidVersions: Android-11Android ID: A-178821491
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 tapjacking/overlay vulnerability in Android's EmergencyCallbackModeExitDialog allows a malicious app to intercept user taps and prematurely exit emergency callback mode. By overlaying a transparent or deceptive UI on top of the exit confirmation dialog, an attacker can trick users into unknowingly confirming the exit of emergency callback mode, potentially leading to local privilege escalation.
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= 11.0CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
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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Verify Android version is 11.0Go to Settings > About Phone > Android version, or run 'adb shell getprop ro.build.version.release'Affected if The device is running Android 11.0 exactly (version equals 11.0)
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Identify apps with overlay permission (SYSTEM_ALERT_WINDOW)Go to Settings > Apps > Special access > Display over other apps, or run 'adb shell dumpsys package <package_name> | grep -i overlay'Affected if Any untrusted or unknown app has the 'Display over other apps' permission granted while in emergency callback mode
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Check for apps with accessibility or root privileges that could exploit overlayReview installed apps in Settings > Apps, looking for unfamiliar or suspicious apps with unusual permissions, especially those requesting overlay or accessibility servicesAffected if A malicious app with overlay capability is installed on the device
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Inspect device lockdown or emergency callback mode configurationCheck if the device has emergency callback mode enabled by reviewing 'adb shell settings get global emergency_callback_mode' or checking carrier-specific emergency settingsAffected if Emergency callback mode is active and the exit confirmation dialog can be overlaid
The environment is affected if running Android 11.0 with any untrusted app granted overlay (SYSTEM_ALERT_WINDOW) permission that could intercept the EmergencyCallbackModeExitDialog confirmation taps.
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 proper touch event filtering and overlay detection mechanisms in the dialog's onCreate method, utilizing window flags (FLAG_SECURE, FLAG_NOT_TOUCHABLE) and input validation to detect and block malicious overlays before processing user confirmation.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2021-0538 — 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-2021-0538 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
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