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Improper LockingWeakness · CWE-667

CVE-2025-1221

MEDIUM · 5.9 CVSS v4.0 Published 2025-07-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
61/100
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
A Zigbee Radio Co-Processor (RCP), which is using SiLabs EmberZNet Zigbee stack, was unable to send messages to the host system (CPCd) due to heavy Zigbee traffic, resulting in a Denial of Service (DoS) attack, Only hard reset will bring the device to normal operation

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

A vulnerability in SiLabs EmberZNet-based Zigbee Radio Co-Processors allows heavy Zigbee traffic to overwhelm the device's communication channel with the host CPCd daemon, causing complete loss of function until a manual hard reset is performed.

MitigationUpdate to any available SiLabs EmberZNet firmware patches addressing this DoS condition; implement Zigbee network traffic monitoring and rate limiting; consider network isolation for critical RCP devices.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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
Adjacent
Complexity
Low
Privileges
Low
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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 if SiLabs EmberZNet RCP hardware is in use
    Check system hardware inventories, device listings, or Zigbee coordinator documentation for SiLabs EmberZNet or Silicon Labs Radio Co-Processor references
    Affected if The environment contains SiLabs EmberZNet-based Zigbee RCP devices
  2. Verify CPCd daemon is running
    Run command to list running processes or services, looking for 'cpcd' or 'cpc-daemon' process
    Affected if CPCd daemon is actively running and managing communication with the RCP
  3. Check EmberZNet firmware version
    Query the RCP firmware version through CPCd logs, diagnostic interfaces, or vendor management tools (command examples: 'cpc-utils' queries, log file inspection at /var/log/cpcd* or similar paths, or vendor-specific CLI tools)
    Affected if Firmware version cannot be verified as patched or falls within an unpatched version range
  4. Assess Zigbee traffic exposure
    Monitor Zigbee network traffic volume using network analyzer tools, controller dashboards, or CPCd logs for high message rates
    Affected if Device is exposed to heavy or burst Zigbee traffic patterns that could trigger the DoS condition
  5. Confirm absence of recent firmware updates
    Review change logs, firmware management records, or system documentation for any recent EmberZNet firmware patches applied to address DoS vulnerabilities
    Affected if No recent firmware updates have been applied and the firmware predates available patches

A user is affected if their environment uses SiLabs EmberZNet-based RCP devices with CPCd daemon and has unpatched firmware exposed to heavy Zigbee traffic

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

Update to any available SiLabs EmberZNet firmware patches addressing this DoS condition; implement Zigbee network traffic monitoring and rate limiting; consider network isolation for critical RCP devices.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,680
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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-2025-1221 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
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