dbcve.org
AndroidOperating system · Google

CVE-2021-0921

HIGH · 7.8 CVSS v3.1 Published 2021-12-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
Remediation priority · High
Zero-click

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 · unedited
In ParsingPackageImpl of ParsingPackageImpl.java, there is a possible parcel serialization/deserialization mismatch due to improper input validation. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11Android ID: A-195962697

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 · moderate confidence

In ParsingPackageImpl.java within the Android framework, improper input validation during parcel deserialization creates a serialization mismatch vulnerability. This allows a local attacker to escalate privileges without requiring user interaction or additional execution privileges. The flaw exists in how package parsing handles serialized parcel data on Android-11.

MitigationThis vulnerability is addressed through system updates released by device manufacturers or Google. Organizations should ensure Android devices receive the latest security patches. Developers building custom Android ROMs must add proper input validation in ParsingPackageImpl's parcel reading methods to verify data integrity before deserialization.

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
AndroidOperating system
Affected:= 11.0

CVSS 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
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check Android version on the device
    Go to Settings > About Phone > Android version, or run 'getprop ro.build.version.release' via ADB shell
    Affected if The device is running Android 11 (version 11.0, API level 30)
  2. Verify the security patch level
    Go to Settings > About Phone > Security patch level, or run 'getprop ro.build.version.security_patch' via ADB shell
    Affected if The security patch level is earlier than December 2021, meaning the CVE-2021-0921 fix is not applied
  3. Confirm ParsingPackageImpl component exists
    On a rooted device or custom ROM build, check for the framework JAR at /system/framework/framework.jar and inspect ParsingPackageImpl.java in the source
    Affected if The device runs a custom ROM built from Android 11 source code without the validation fix in ParsingPackageImpl parcel reading methods
  4. Check for package manager service behavior
    Observe package installation and parsing behavior via logcat filtering for 'PackageParser' or 'ParsingPackageImpl' messages during APK installs
    Affected if The device exhibits unexpected parcel deserialization behavior during package parsing operations

The device is affected if it runs Android 11 with a security patch level before December 2021, as the vulnerability exists only in Android 11 and was fixed in the December 2021 security update.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

This vulnerability is addressed through system updates released by device manufacturers or Google. Organizations should ensure Android devices receive the latest security patches. Developers building custom Android ROMs must add proper input validation in ParsingPackageImpl's parcel reading methods to verify data integrity before deserialization.

Recommended fix High confidence

Android 12 (API 31) or January 2022 Security Patch Level for Android 11

  1. Upgrade the device to Android 12 (API level 31) or later, which contains the fix for this vulnerability in ParsingPackageImpl.java
  2. Alternatively, apply the January 2022 Android Security Patch Level (SPL) to Android 11 devices, which backports the CVE-2021-0921 fix
  3. Verify the patch level by going to Settings > About Phone > Android version and confirming the Security patch level is January 2022 or later
  4. For enterprise/managed devices, use MDM or OTA update infrastructure to push the update to affected devices
Caveat Android 12 may introduce breaking changes in app behavior; test critical applications before broad deployment. Some devices may have delayed OTA availability from carriers.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Android Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA8.0 h
44.0 hours of engineering $7,720
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-0921 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data