CVE-2023-21309
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 · uneditedIn libcore, there is a possible out of bounds read due to a missing bounds check. This could lead to local information disclosure 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 · moderate confidenceIn libcore (Android's core library), an out of bounds read vulnerability exists due to a missing bounds check. The flaw allows a local attacker to read sensitive information from memory beyond intended buffer boundaries without requiring any special privileges or user interaction.
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< 14.0CVSS 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
- None
- Availability
- None
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
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 checksWork through these to decide whether this CVE applies to you.
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Check Android versionNavigate to Settings > About Phone (or About Device) and view the Android version numberAffected if The reported Android version is 13.x or lower (versions below 14.0 are affected)
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Verify security patch levelGo to Settings > About Phone > Android version, then look for 'Security patch level' or 'Build number' information. This indicates whether vendor patches have been appliedAffected if The security patch level is earlier than the vendor patch date for CVE-2023-21309 (or patch level is not displayed, indicating unpatched system)
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Check libcore library version (optional)On rooted devices or through ADB, examine the libcore library file. In Android, libcore is part of the framework. You can check via 'adb shell dumpsys package libcore' or by inspecting the system library in /system/lib/ or /system/framework/Affected if The libcore library version cannot be determined or is older than the version bundled with Android 14.0
If the Android device runs version 13.x or lower without the CVE-2023-21309 vendor patch, the environment is vulnerable to the out-of-bounds read in libcore.
Generated from the published advisory. Verify against your own configuration.
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 · scoped14.0
Apply the vendor-supplied patch for CVE-2023-21309 to the libcore library. As this is a system library fix, ensure the update is integrated into the Android build and deployed via standard system update mechanisms.
Android 14.0
- Upgrade the device to Android 14.0 or later to resolve the out-of-bounds read vulnerability in libcore.
- Verify the Android version after upgrade by checking Settings > About Phone > Android version to confirm it shows 14.0 or higher.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation2.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,160.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-21309 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-21309 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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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