CVE-2023-4489

Unauthorized S0 access via pre-initialization key generation

Published Dec 14, 2023 · Updated May 21, 2025

Predictable key generation in Silicon Labs Z/IP Gateway SDK 7.18.3 and earlier allows physically proximate attackers to gain S0 network access. At startup, the first S0 encryption key is generated before the pseudorandom number generator is initialized, making the key predictable. Physical proximity and Z-Wave radio access are required; the predicted key permits unauthorized participation in the encrypted S0 network.

CVSS severity6.4
Medium
EPSS probability0.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Predictable key generation in Silicon Labs Z/IP Gateway SDK 7.18.3 and earlier allows physically proximate attackers to gain S0 network access. At startup, the first S0 encryption key is generated before the pseudorandom number generator is initialized, making the key predictable. Physical proximity and Z-Wave radio access are required; the predicted key permits unauthorized participation in the encrypted S0 network.

The record

CVE
CVE-2023-4489
Published
Dec 14, 2023
Updated
May 21, 2025
Vendor
Sigma Designs
Product
Z/IP Gateway SDK
Classifications
CWE-1279, CAPEC-59
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 14, 2023CVE publishedPublication date reported by the CVE source.
  2. May 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=7.18.3

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

Sigma Designs · Z/IP Gateway SDKversion=0 <=7.18.3

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
6.4Silicon LabsCVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1279Cryptographic Operations are run Before Supporting Units are Ready
CAPEC-59Session Credential Falsification through Prediction

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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