CVE-2021-39796Public exploit

Local privilege escalation via tap-through overlay

Published Apr 12, 2022 · Updated Aug 4, 2024

Tapjacking in Android 10, 11, 12, and 12L allows local users to trick a victim into installing a harmful app through an overlay. HarmfulAppWarningActivity fails to hide non-system overlay windows, allowing taps to pass through an attacker's overlay and start the harmful activity. Exploitation requires an app with user-level execution privileges and a victim tap, after which the harmful app is installed.

CVSS severity7.3
High
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Tapjacking in Android 10, 11, 12, and 12L allows local users to trick a victim into installing a harmful app through an overlay. HarmfulAppWarningActivity fails to hide non-system overlay windows, allowing taps to pass through an attacker's overlay and start the harmful activity. Exploitation requires an app with user-level execution privileges and a victim tap, after which the harmful app is installed.

The record

CVE
CVE-2021-39796
Published
Apr 12, 2022
Updated
Aug 4, 2024
Vendor
Google Cloud
Product
Android
Classifications
CWE-1021, T1404
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 12, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Android-10 Android-11 Android-12 Android-12L

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Google Cloud · Androidversion=Android-10 Android-11 Android-12 Android-12L

Published CVSS scores

6.9NIST NVDAV:L/AC:M/Au:N/C:C/I:C/A:C
7.3NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1021Improper Restriction of Rendered UI Layers or Frames
T1404Exploitation for Privilege Escalation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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