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AndroidOperating system · Google

CVE-2023-21159

MEDIUM · 6.7 CVSS v3.1 Published 2023-06-28
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 Parse of simdata.cpp, there is a possible out of bounds write due to a missing bounds check. 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-263783565References: 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

This is a bounds check vulnerability in the Android kernel's SIM data parser (simdata.cpp). The Parse function lacks proper boundary validation when processing SIM data, allowing an out-of-bounds write that can be leveraged for local privilege escalation from System privileges.

MitigationApply the vendor patch for Android kernel that adds proper bounds checking in the simdata.cpp Parse function. Since this is a kernel-level fix, ensure the patch is integrated into the device's firmware updates.

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
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. Check Android Security Patch Level
    Go to Settings > About Phone > Security Patch Level. Alternatively, run 'getprop ro.build.version.security_patch' via ADB shell.
    Affected if The Security Patch Level is earlier than May 2023 (the month CVE-2023-21159 was patched in Android's monthly security bulletin)
  2. Verify kernel version includes the fix
    Check the kernel version via 'uname -r' or 'cat /proc/version'. Cross-reference with Google's Android kernel common patches repository for the simdata.cpp bounds check commit.
    Affected if The kernel version predates the May 2023 Android security update or does not contain the bounds checking changes in simdata.cpp
  3. Confirm SIM functionality is present
    Check if the device has SIM card capability and the SIM toolkit/STK is enabled. Run 'pm list packages | grep stk' or verify SIM card detection in Settings > About Phone > SIM Status.
    Affected if The device has active SIM functionality and the simdata parser code path can be triggered (required for exploitation)
  4. Check for kernel symbols related to simdata parser
    If you have root access, examine /proc/kallsyms or the kernel image for symbols related to 'simdata' and 'Parse'. Use 'strings <kernel_img> | grep -i simdata' to locate the affected code section.
    Affected if The simdata Parse function exists without proper bounds checking as identified in the CVE (out-of-bounds write absent)
  5. Verify vendor firmware update status
    Contact the device vendor or check their support documentation for the specific Android security bulletin (May 2023) implementation status. Run 'getprop ro.vendor.version' and compare against vendor release notes.
    Affected if The vendor has not released or deployed the May 2023 Android Security Bulletin update containing the simdata.cpp fix

A device is affected if it lacks the May 2023 Android security patch that adds bounds checking in the kernel simdata.cpp Parse function, and the device has active SIM functionality that can trigger the vulnerable code path.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor patch for Android kernel that adds proper bounds checking in the simdata.cpp Parse function. Since this is a kernel-level fix, ensure the patch is integrated into the device's firmware updates.

Fix this in Android Scoped from the published advisory
  • Consultation2.0 h
  • Implementation6.0 h
  • Testing12.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,000
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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-2023-21159 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
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