dbcve.org
AndroidOperating system · Google

CVE-2023-21218

CRITICAL · 9.8 CVSS v3.1 Published 2023-12-04
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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 PMRChangeSparseMemOSMem of physmem_osmem_linux.c, there is a possible out of bounds write due to an incorrect bounds check. This could lead to local escalation of privilege in the kernel with no additional execution privileges needed. User interaction is not needed for exploitation.

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 kernel-level out-of-bounds write vulnerability exists in the Linux kernel's physical memory management subsystem (physmem_osmem_linux.c). The PMRChangeSparseMemOSMem function contains an incorrect bounds check that allows writing beyond allocated memory boundaries, enabling a local attacker to escalate privileges to root without requiring user interaction or additional execution privileges.

MitigationApply the official Linux kernel security patch that corrects the bounds check in PMRChangeSparseMemOSMem. This requires updating the kernel to a version that includes the fix, followed by a system reboot.

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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 device runs Google Android
    Check /system/build.prop for ro.build.fingerprint or run 'getprop ro.build.fingerprint' to verify the device is running Google Android OS
    Affected if Device is not running Google Android - this CVE only affects Android devices
  2. Check kernel version
    Run 'uname -r' or check /proc/version to obtain the running kernel version
    Affected if Running any kernel version on Google Android - per the advisory, all Android versions are affected
  3. Identify PMRChangeSparseMemOSMem usage
    Examine kernel configuration or system logs for traces of the physmem_osmem_linux.c module and PMRChangeSparseMemOSMem function - this may appear in kernel debug logs or memory management subsystem outputs
    Affected if The function exists in the kernel source for the device - the vulnerability is present in all Android kernels containing this physical memory management code

If the device runs Google Android, it is affected by this CVE because all Android versions contain the vulnerable bounds check in the PMRChangeSparseMemOSMem function within the Linux kernel's physical memory management subsystem.

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 official Linux kernel security patch that corrects the bounds check in PMRChangeSparseMemOSMem. This requires updating the kernel to a version that includes the fix, followed by a system reboot.

Recommended fix High confidence

Latest available Android security patch level (July 2023 or later) that includes the CVE-2023-21218 kernel patch

  1. Check the Android Security Bulletin for July 2023 (or subsequent bulletins) for CVE-2023-21218 to identify the specific patch level that addresses this vulnerability
  2. Apply the monthly Android security update that includes the fix for this kernel vulnerability
  3. On supported devices, ensure the system is updated to the latest available Android version with the corresponding kernel patch
Caveat Kernel patches are included in monthly Android security updates; ensure device compatibility and backup data before applying updates

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

Fix this in Android Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA3.0 h
20.0 hours of engineering $3,420
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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-2023-21218 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