CVE-2023-4420Network attack vector

Sensitive-data disclosure via cleartext communication

Published Aug 24, 2023 · Updated Jun 1, 2026

Cleartext transmission in SICK AG LMS5xx firmware allows remote attackers to disclose and manipulate communication data via man-in-the-middle interception. The sensor and client exchange data without Transport Layer Security, so an on-path attacker can eavesdrop and alter transmitted messages. No authentication or user interaction is required, but the attacker must occupy the network path; confidentiality and integrity are affected.

CVSS severity7.4
High
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Cleartext transmission in SICK AG LMS5xx firmware allows remote attackers to disclose and manipulate communication data via man-in-the-middle interception. The sensor and client exchange data without Transport Layer Security, so an on-path attacker can eavesdrop and alter transmitted messages. No authentication or user interaction is required, but the attacker must occupy the network path; confidentiality and integrity are affected.

The record

CVE
CVE-2023-4420
Published
Aug 24, 2023
Updated
Jun 1, 2026
Vendor
SICK AG
Product
LMS5xx
Classifications
CWE-311, CWE-319, T1040, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 24, 2023CVE publishedPublication date reported by the CVE source.
  2. Jun 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0 <*
  2. Affected versionversion=all firmware versions

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SICK AG · LMS5xxversion=0 <*; version=all firmware versions

Published CVSS scores

9.8SICK AGCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.4NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-311Missing Encryption of Sensitive Data
CWE-319Cleartext Transmission of Sensitive Information
T1040Network Sniffing
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo