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AndroidOperating system · Google

CVE-2021-0657

MEDIUM · 6.7 CVSS v3.1 Published 2021-11-18
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 stack-based buffer overflow. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation. Patch ID: ALPS05672103; Issue ID: ALPS05672103.

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 stack-based buffer overflow exists in the apusys (AI Processing Unit subsystem) driver in MediaTek Android kernels. The vulnerability allows a local attacker with System-level access to achieve privilege escalation by overflowing a stack-allocated buffer, potentially executing arbitrary code in kernel context.

MitigationApply the vendor patch ALPS05672103 to the apusys driver, which adds proper bounds checking to prevent the stack buffer overflow. This is a kernel-level fix requiring a system update.

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

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. Confirm Android version is affected
    Go to Settings > About Phone > Android version, or run 'getprop ro.build.version.release' via adb shell
    Affected if Version displays 10.0 or 11.0 exactly
  2. Verify MediaTek chipset is present
    Run 'getprop ro.hardware' or 'cat /proc/cpuinfo' via adb shell and look for MediaTek or MTK identifiers
    Affected if The device uses a MediaTek SoC (the apusys driver is MediaTek-specific)
  3. Check if apusys driver is loaded
    Run 'ls -la /dev/apus*' or 'cat /proc/modules' via adb shell to list apusys-related driver entries
    Affected if The apusys driver module or device node exists on the system
  4. Inspect kernel patch level
    Run 'getprop ro.build.version.security_patch' via adb shell to check the Android security patch date
    Affected if The security patch level is earlier than the date when ALPS05672103 was applied (vendor-specific, typically post-fix)

The environment is affected if the device runs Android 10.0 or 11.0 on a MediaTek chipset with the apusys driver present and lacks the vendor security patch containing ALPS05672103.

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 ALPS05672103 to the apusys driver, which adds proper bounds checking to prevent the stack buffer overflow. This is a kernel-level fix requiring a system update.

Recommended fix High confidence

Android 12.0 (API 31) or later, which includes the fix in the 2021-06-01 Security Patch Level

  1. Obtain the MediaTek patch ALPS05672103 for the apusys driver from MediaTek's official corp.mediatek.com source or through your MediaTek representative
  2. Apply the patch to the Android kernel source or vendor firmware for affected MediaTek-based devices running Android 10.0 or 11.0
  3. Verify the patch compiles successfully and integrates with the apusys driver module
  4. Deploy the patched vendor image or OTA update to affected devices
  5. Confirm the fix resolves the stack-based buffer overflow in apusys that could allow local privilege escalation
Caveat Upgrading to Android 12 may introduce compatibility issues with existing apps; ensure app compatibility testing is performed before full deployment

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

Fix this in Android Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing10.0 h
  • Review / QA5.0 h
33.0 hours of engineering $5,760
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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-2021-0657 in production — separate from our analysis above.

No notes yet

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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