dbcve.org
AndroidOperating system · Google

CVE-2021-0894

MEDIUM · 6.7 CVSS v3.1 Published 2021-12-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
69/100
Remediation priority · Elevated
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 apusys, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation. Patch ID: ALPS05672107; Issue ID: ALPS05672038.

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 · high confidence

A missing bounds check in MediaTek's apusys (Advanced Power Management Unified System) allows an out-of-bounds write vulnerability. This local privilege escalation flaw requires System execution privileges to exploit but could allow an attacker to gain elevated access. The vulnerability stems from inadequate validation before a memory write operation in the power management subsystem.

MitigationApply the vendor patch ALPS05672107 which addresses the missing bounds check in apusys. As this is a local privilege escalation requiring System-level access, prioritize patching devices with MediaTek chipsets running affected Android versions.

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:= 10.0= 11.0= 12.0

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
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:H/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. Identify the chipset vendor
    Check /proc/cpuinfo or use 'getprop ro.hardware' or 'cat /sys/devices/system/cpu/cpu0/cpu_variant' to determine if the device uses a MediaTek chipset. The vulnerability exists only in MediaTek's apusys subsystem.
    Affected if The device does not have a MediaTek chipset - this vulnerability does not apply to Qualcomm, Samsung, or other non-MediaTek platforms.
  2. Verify Android version
    Run 'getprop ro.build.version.release' or check Settings > About Phone > Android version to determine the installed Android OS version.
    Affected if The Android version is 10.0, 11.0, or 12.0 - these are the affected versions listed in the CVE.
  3. Check for apusys module presence
    List the kernel modules or check /sys/module/ for 'apusys' or 'mtk_apusys', or inspect 'ls -la /vendor/lib/modules/' for apusys-related drivers. The vulnerability resides in this power management subsystem.
    Affected if The apusys module is not present on the device - the vulnerable component is not installed.
  4. Inspect patch level
    Run 'getprop ro.build.version.security_patch' to check the security patch date. Compare against the vendor patch ALPS05672107 release date for MediaTek devices.
    Affected if The security patch level is older than the patch addressing CVE-2021-0894, indicating the bounds check fix has not been applied.

A device is affected if it runs Android 10, 11, or 12 on a MediaTek chipset with the apusys power management subsystem present and without the ALPS05672107 patch applied.

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

Apply the vendor patch ALPS05672107 which addresses the missing bounds check in apusys. As this is a local privilege escalation requiring System-level access, prioritize patching devices with MediaTek chipsets running affected Android versions.

Recommended fix Moderate confidence
  1. Contact MediaTek for the ALPS05672107 patch through your device manufacturer or MediaTek's official support channels
  2. Apply the patch through your device manufacturer's security update process
  3. Verify the patch has been applied by checking your device's security patch level in Settings > About Phone > Security Patch Level
Caveat Patches for MediaTek hardware components must be obtained through device manufacturer channels; availability varies by carrier and device

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

Fix this in Android Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing3.0 h
  • Review / QA2.0 h
8.0 hours of engineering $1,390
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Scan for this in your stack

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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-2021-0894 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