CVE-2021-0391

Local privilege escalation via obscured account chooser

Published Mar 10, 2021 · Updated Aug 3, 2024

Improper UI-layer restriction in Android 8.1 through 11 allows local users to learn whether an account exists through a tapjacking overlay. ChooseTypeAndAccountActivity.onCreate accepts obscured user interaction instead of rejecting touches while another app overlays the account chooser. A malicious app with User execution privileges must draw the overlay and induce user interaction, enabling unauthorized account discovery and local privilege elevation.

CVSS severity7.8
High
EPSS probability0.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper UI-layer restriction in Android 8.1 through 11 allows local users to learn whether an account exists through a tapjacking overlay. ChooseTypeAndAccountActivity.onCreate accepts obscured user interaction instead of rejecting touches while another app overlays the account chooser. A malicious app with User execution privileges must draw the overlay and induce user interaction, enabling unauthorized account discovery and local privilege elevation.

The record

CVE
CVE-2021-0391
Published
Mar 10, 2021
Updated
Aug 3, 2024
Vendor
Google Cloud
Product
Android
Classifications
CWE-1021
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 10, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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-11 Android-8.1 Android-9 Android-10

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Google Cloud · Androidversion=Android-11 Android-8.1 Android-9 Android-10

Published CVSS scores

6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1021Improper Restriction of Rendered UI Layers or Frames

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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