dbcve.org
AndroidOperating system · Samsung

CVE-2023-21504

CRITICAL · 9.8 CVSS v3.1 Published 2023-05-04
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
Potential buffer overflow vulnerability in mm_Plmncoordination.c in Shannon baseband prior to SMR May-2023 Release 1 allows remote attackers to cause invalid memory access.

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

Buffer overflow vulnerability in the mm_Plmncoordination.c module of Shannon baseband firmware allows remote attackers to cause invalid memory access by overflowing a buffer in the PLMN coordination functionality. This critical flaw in baseband processor firmware affects devices running Shannon baseband prior to the SMR May-2023 Release 1.

MitigationUpdate affected devices to Shannon baseband firmware version SMR May-2023 Release 1 or later to patch the buffer overflow in mm_Plmncoordination.c. Since this is a baseband firmware vulnerability, users should apply carrier or device manufacturer 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:= 11.0= 12.0= 13.0

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 is a Samsung Android phone
    Check the device manufacturer and model in Settings > About Phone, or look for Samsung branding on the device
    Affected if Device is not a Samsung Android device - this vulnerability only affects Samsung Shannon baseband firmware
  2. Verify Android OS version
    Go to Settings > About Phone > Android version, or run 'adb shell getprop ro.build.version.release'
    Affected if Android version is NOT 11.0, 12.0, or 13.0 - these are the only affected Android versions listed
  3. Identify the baseband firmware version
    Run 'adb shell getprop gsm.version.baseband' or check Settings > About Phone > Baseband version. Alternatively, use AT command 'AT+CGMR' via a terminal app or serial debug interface
    Affected if Unable to retrieve baseband version - this indicates non-Shannon or unidentified baseband
  4. Confirm Shannon baseband processor
    The baseband version string typically contains 'Shannon' or is from Samsung's baseband firmware lineage. Compare the retrieved baseband string against known Shannon naming conventions
    Affected if Baseband is not Shannon - this vulnerability is specific to Shannon baseband firmware only
  5. Compare baseband version to affected release
    Check if the baseband firmware version predates SMR May-2023 Release 1. The fixed version is SMR May-2023 Release 1 or later
    Affected if Baseband firmware version is prior to SMR May-2023 Release 1 - this indicates the device is running a vulnerable version

A Samsung Android device on version 11.0, 12.0, or 13.0 with Shannon baseband firmware prior to SMR May-2023 Release 1 is affected by this 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

Update affected devices to Shannon baseband firmware version SMR May-2023 Release 1 or later to patch the buffer overflow in mm_Plmncoordination.c. Since this is a baseband firmware vulnerability, users should apply carrier or device manufacturer firmware updates.

Recommended fix High confidence

SMR May-2023 Release 1

  1. Check if your Samsung device with Shannon baseband has received the SMR May-2023 security update
  2. Go to Settings > Security & privacy > Security update on your Samsung device
  3. Verify the security patch level is May-2023 or later
  4. If the update is not available, check for manual updates in Settings > Software update > Download and install
  5. Contact your device manufacturer or carrier if the update is not yet available for your specific model

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-2023-21504 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