CVE-2021-39754

Local app-presence disclosure via ContextImpl side channel

Published Mar 30, 2022 · Updated Aug 4, 2024

Information disclosure in Android 12L ContextImpl allows local users to determine whether another app is installed without query permission. ContextImpl exposes an observable discrepancy when an unprivileged app probes for another package, bypassing package-visibility filtering that normally withholds unapproved installation data. Exploitation requires code execution as a local app but needs no additional privileges or user interaction; the disclosed consequence is limited to app-presence information.

CVSS severity5.5
Medium
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

Information disclosure in Android 12L ContextImpl allows local users to determine whether another app is installed without query permission. ContextImpl exposes an observable discrepancy when an unprivileged app probes for another package, bypassing package-visibility filtering that normally withholds unapproved installation data. Exploitation requires code execution as a local app but needs no additional privileges or user interaction; the disclosed consequence is limited to app-presence information.

The record

CVE
CVE-2021-39754
Published
Mar 30, 2022
Updated
Aug 4, 2024
Vendor
Google Cloud
Product
Android
Classifications
CWE-203, T1418
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 30, 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-12L

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Google Cloud · Androidversion=Android-12L

Published CVSS scores

2.1NIST NVDAV:L/AC:L/Au:N/C:P/I:N/A:N
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

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.

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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-203Observable Discrepancy
T1418Software Discovery

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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