How severe is CVE-2018-5440?

CVE-2018-5440 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2018-5440 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-5440?

CVE-2018-5440 primarily affects 3s-software Codesys Runtime System. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-5440?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2018-5440 published?

CVE-2018-5440 was published on 2018-02-15 and last updated on 2026-06-17.

CVE-2018-5440

CVE-2018-5440 is a critical-severity vulnerability in 3s-software Codesys Runtime System with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 3% (86th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: 3s-software Codesys Runtime System
Published: 2018-02-15
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2018-5440?: 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.
How severe is CVE-2018-5440?: CVE-2018-5440 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2018-5440 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-5440?: CVE-2018-5440 primarily affects 3s-software Codesys Runtime System. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-5440?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2018-5440 published?: CVE-2018-5440 was published on 2018-02-15 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:3s-software:codesys_runtime_system:*:*:*:*:*:*:*:*
cpe:2.3:a:3s-software:codesys_web_server:2.3:*:*:*:*:*:*:*

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