CVE-2021-39691

Local privilege escalation via slippery touch forwarding

Published Jun 15, 2022 · Updated Aug 4, 2024

Tapjacking in Android 10 through 12 WindowManager allows local users to escalate privileges by redirecting a victim's touch input. WindowManager accepts FLAG_SLIPPERY on letterbox and related windows, causing a touch that begins on an obscuring window to continue into the underlying window. A local user must place a crafted window over a privileged interface and induce the victim to interact, after which unintended actions execute with the victim's authority.

CVSS severity7.3
High
EPSS probability0.11%
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 through 12 WindowManager allows local users to escalate privileges by redirecting a victim's touch input. WindowManager accepts FLAG_SLIPPERY on letterbox and related windows, causing a touch that begins on an obscuring window to continue into the underlying window. A local user must place a crafted window over a privileged interface and induce the victim to interact, after which unintended actions execute with the victim's authority.

The record

CVE
CVE-2021-39691
Published
Jun 15, 2022
Updated
Aug 4, 2024
Vendor
Google Cloud
Product
Android
Classifications
CWE-1021, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 15, 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

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

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

Published CVSS scores

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

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-1021Improper Restriction of Rendered UI Layers or Frames
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

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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