dbcve.org
AndroidOperating system · Google

CVE-2021-39735

MEDIUM · 6.4 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 →
66/100
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 gasket_alloc_coherent_memory of gasket_page_table.c, there is a possible memory corruption due to a race condition. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-151455484References: 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 race condition in gasket_alloc_coherent_memory within the Google Android kernel gasket driver (gasket_page_table.c) allows local attackers to achieve memory corruption, potentially enabling privilege escalation from the Android System execution context.

MitigationApply the vendor-provided kernel security patch for Android ID A-151455484; until patched, minimize exposure by restricting unnecessary kernel module loading and monitoring for suspicious driver interactions.

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

CVSS:3.1/AV:L/AC:H/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. Check if the gasket kernel module is loaded
    Run 'lsmod | grep -i gasket' or list contents of '/sys/module/' directory for gasket-related modules
    Affected if A gasket module (e.g., gasket, gasket_page_table) is loaded or present in the module directory
  2. Check for gasket device nodes
    Run 'ls -la /dev/gasket*' or 'ls -la /dev/*gasket*' to enumerate gasket character devices
    Affected if Gasket device nodes exist in /dev indicating the driver is active
  3. Verify kernel version against patch date
    Run 'uname -a' to get the kernel version; the fix was released as part of Android security updates after late 2021
    Affected if Kernel version predates the vendor security patch for Android ID A-151455484 (approximately late 2021 or earlier)
  4. Check kernel configuration for GASKET driver support
    Check '/boot/config-*' or '/proc/config.gz' for 'CONFIG_GASKET' or 'CONFIG_GASKET_DRIVER' kernel configuration options set to 'y' or 'm'
    Affected if The GASKET driver is compiled into the kernel (y) or as a loadable module (m)
  5. Scan for gasket driver files on the system
    Search for 'gasket_page_table.ko' using 'find /lib/modules -name "*gasket*" 2>/dev/null'
    Affected if Gasket kernel module files exist in the system's module directories

A user is affected if the gasket kernel driver is present and loaded on a Google Android device running a kernel version predating the Android ID A-151455484 security patch.

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-provided kernel security patch for Android ID A-151455484; until patched, minimize exposure by restricting unnecessary kernel module loading and monitoring for suspicious driver interactions.

Recommended fix Moderate confidence

Android security patch level 2021-11-01 or later (kernel version with fix for race condition in gasket_alloc_coherent_memory)

  1. Upgrade to the latest Android security patch level (2021-11-01 or later) which contains the fix for this vulnerability
  2. Apply any available system updates from your device manufacturer that include the November 2021 Android Security Bulletin patches
  3. For kernel-level remediation, ensure the gasket driver is updated to a version that includes the race condition fix in gasket_page_table.c
Caveat May require device manufacturer support; some older devices may not receive kernel-level patches

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
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,760
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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-2021-39735 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