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AndroidOperating system · Google

CVE-2023-21216

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 arbitrary code execution due to a use after free. 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 use-after-free vulnerability exists in the PMRChangeSparseMemOSMem function in physmem_osmem_linux.c within the Linux kernel's physical memory management subsystem. The memory corruption bug can be exploited by a local attacker to achieve arbitrary code execution at kernel privilege level, leading to local privilege escalation without requiring any additional privileges or user interaction.

MitigationApply the upstream Linux kernel patch that fixes the use-after-free in PMRChangeSparseMemOSMem. Deploy the patched kernel version to all affected systems and schedule reboots as needed.

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. Identify the kernel version
    On Android, run 'cat /proc/version' or check 'Settings > About Phone > Kernel Version' to retrieve the running kernel version
    Affected if The device runs any unpatched Android kernel version
  2. Check for physmem_osmem_linux.c module
    Search for the physmem_osmem_linux.ko module or the physmem_osmem_linux.c source file in the kernel build: 'find /system/lib/modules -name "physmem_osmem*"' or grep for 'physmem_osmem' in /proc/kallsyms
    Affected if The kernel includes the physmem_osmem Linux kernel module (indicating the vulnerable code path exists)
  3. Verify PMRChangeSparseMemOSMem function presence
    Check if the PMRChangeSparseMemOSMem function symbol exists in the running kernel: 'grep -i PMRChangeSparseMemOSMem /proc/kallsyms' or examine the kernelSymbols file
    Affected if The function PMRChangeSparseMemOSMem is exported or present in the kernel, indicating the vulnerable code path is compiled in
  4. Confirm Android framework usage
    Verify the device is running Android OS by checking '/system/build.prop' for 'ro.build.fingerprint' or running 'getprop ro.build.version.release'
    Affected if The device runs Google Android OS (the only product listed as affected)

A device is affected if it runs Google Android with a kernel that contains the physmem_osmem_linux.c module and PMRChangeSparseMemOSMem function without the upstream Linux kernel patch applied to fix the use-after-free vulnerability.

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 Linux kernel patch that fixes the use-after-free in PMRChangeSparseMemOSMem. Deploy the patched kernel version to all affected systems and schedule reboots as needed.

Recommended fix Moderate confidence

Android November 2023 Security Bulletin (or later) - kernel patch level 2023-11-01 or higher

  1. Check your Android device's current security patch level in Settings > About Phone > Android version
  2. Verify if your device has received the November 2023 Android Security Update or later
  3. If not available, contact your device manufacturer or carrier for the latest security patch
  4. For custom ROMs or AOSP builds, ensure you are running a kernel version that includes the fix for CVE-2023-21216 in physmem_osmem_linux.c
  5. The fix addresses a use-after-free vulnerability in PMRChangeSparseMemOSMem that could allow local privilege escalation in the kernel
Caveat Security updates may have minimal compatibility impact; major Android version upgrades carry standard upgrade risks

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
  • Testing16.0 h
  • Review / QA8.0 h
36.0 hours of engineering $6,080
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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-2023-21216 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