dbcve.org
AndroidOperating system · Google

CVE-2021-39732

HIGH · 7.8 CVSS v3.1 Published 2022-03-16
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 copy_io_entries of lwis_ioctl.c, there is a possible out of bounds write due to an integer overflow. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-205992503References: N/A

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

A kernel integer overflow vulnerability exists in the copy_io_entries function within lwis_ioctl.c. The function allocates a buffer based on user-controlled or computed sizes without proper integer overflow validation, allowing an out-of-bounds write that can be exploited for local privilege escalation to root.

MitigationApply the upstream kernel patch for A-205992503 which adds proper bounds checking and integer overflow validation in copy_io_entries. Update Android kernel to a version containing the fix.

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:all versions

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. Verify Android kernel in use
    Run 'uname -r' or check /proc/version to identify the kernel version and build information
    Affected if The device runs a Google Android kernel (any version) and has not received the A-205992503 patch
  2. Check if lwis driver is present
    Look for lwis_ioctl module or driver: ls -la /sys/module/lwis* or check /dev for lwis device nodes
    Affected if The lwis driver module is loaded or the device node exists, making the vulnerable code path reachable
  3. Inspect copy_io_entries source
    If you have access to the kernel source, locate lwis_ioctl.c and search for the copy_io_entries function to verify if bounds checking is present
    Affected if The source code lacks proper integer overflow validation and size checks before buffer allocation in this function
  4. Check kernel build config for lwis
    Examine kernel config (usually in /boot/config-* or /proc/config.gz) for CONFIG_LWIS or related CONFIG options
    Affected if The lwis driver is enabled in the kernel configuration (CONFIG_LWIS=y or =m)
  5. Identify kernel patch level
    Check Android security patch level in Settings > About Phone > Android version, or run 'getprop ro.build.version.security_patch'
    Affected if The security patch level is earlier than the date the A-205992503 fix was released (November 2021 or later)

A user is affected if their Android device uses a kernel with the lwis driver enabled and has not been patched with the A-205992503 fix addressing the integer overflow in copy_io_entries.

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 upstream kernel patch for A-205992503 which adds proper bounds checking and integer overflow validation in copy_io_entries. Update Android kernel to a version containing the fix.

Recommended fix High confidence

Android Security Patch Level 2021-12-01 or later (or latest available)

  1. Check current Android Security Patch Level on the device via Settings > About Phone > Security Patch Level
  2. Contact your device manufacturer or carrier for the specific security update containing the fix for CVE-2021-39732
  3. Update to the latest available Android security update that includes the December 2021 Android Security Bulletin or later patches
  4. If no update is available from the manufacturer, consider upgrading to a device that receives regular security updates
Caveat Security updates are backward-compatible and low-risk; however, older devices may stop receiving updates

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

Fix this in Android Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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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-2021-39732 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