CVE-2017-3735

Festo CODESYS Development System — vulnerability CVE-2017-3735

While parsing an IPAddressFamily extension in an X.509 certificate, it is possible to do a one-byte overread. This would result in an incorrect text display of the certificate. This bug has been present since 2006 and is present in all versions of OpenSSL before 1.0.2m and 1.1.0g.

CVSS 5.3Patch available

This record: live connection— last retrieved: 7 November 2026 at 01:34.

Vendor

Festo

Products

CODESYS Development System, Automation Suite, Controller CECC-D, Controller CECC-LK, Controller CECC-S

up to version vers:generic/<2.8.0.138

Published

28 August 2017

Last modified

17 June 2026

Original source information

Taken directly from NVD, CISA or the vendor — sometimes in English, unchanged from the source.

Technical description

CVSS 3.0 — vector details

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Attack vector

NETWORK

Privileges required

NONE

User interaction

NONE

Confidentiality

None

Integrity

Limited

Availability

None

EPSS — Exploit Prediction Scoring System

Probability of exploitation within 30 days

21.0%

Percentile

98e

Source: FIRST.org, updated on 6 November 2026.

Patch information

Starting from Festo Automation Suite version 2.8.0.138, Codesys is no longer bundled with the suite and must be downloaded and installed separately by the customer. To mitigate this vulnerability customers are advised to: Download the latest, patched version of Codesys directly from the official Codesys website. Follow the installation and update instructions provided by Codesys to ensure all security fixes are applied. Regularly monitor Codesys security advisories and apply updates promptly. Maintain the Festo Automation Suite connector up to date by installing FAS updates as released by Festo.

IACS Radar assessment

Our own interpretation and context for the source data above.

IACS Radar assessment

Our own interpretation and context for this vulnerability — not an official source.

IACS Radar priority score

39/ 100

Based on CVSS 5.3, EPSS 21.0%, industrial relevance 40/100.

Combines CVSS, EPSS, KEV status, industrial relevance and exposure relevance — a complement to, not a replacement for, the individual scores below and above.

Conditions for exploitation

•Network access to the affected device or segment is required.
•No valid credentials are needed.
•No user interaction required.

Operational impact & energy relevance

Limited impact on availability; the risk lies mainly with confidentiality or integrity of process data.

No strong energy-sector-specific signals recognised; general OT/ICS relevance.

Recommended defensive measures

•Apply the latest firmware or software update and validate its integrity.
•Restrict network access to the affected device to a dedicated OT management segment.
•Implement network segmentation in line with zones and conduits (IEC 62443-3-2).
•Monitor for abnormal protocol traffic using an OT-aware detection system.

Industrial relevance score

40/ 100

• Mentioned in an official CISA ICS advisory, which confirms direct relevance to industrial control systems.

Classification is provisional; manual verification by an OT security analyst is recommended.

Classified by IACS Radar-analysepijplijn (geautomatiseerd) on 7 November 2026.

IEC 62443 mapping

IEC 62443-4-1FR3 · Systeemintegriteit

Automatic IACS Radar assessment based on the reported CWE weakness classification; not an official certification statement.

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