Is CVE-2018-5440 actively exploited?

No active exploitation of CVE-2018-5440 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2018-5440 be exploited remotely?

Yes. CVE-2018-5440 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2018-5440?

CVE-2018-5440 has a CVSS score of 9.8 (CRITICAL).

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CRITICAL

CVE-2018-5440

CWE-121Published: February 15, 2018· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official Description

A Stack-based Buffer Overflow issue was discovered in 3S-Smart CODESYS Web Server. Specifically: all Microsoft Windows (also WinCE) based CODESYS web servers running stand-alone Version 2.3, or as part of the CODESYS runtime system running prior to Version V1.1.9.19. A crafted request may cause a buffer overflow and could therefore execute arbitrary code on the web server or lead to a denial-of-service condition due to a crash in the web server.

NVD Source

Technical Analysis

CVE-2018-5440 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.