CVE-2021-29242 Festo CVE debrief

Who should care

Organizations using Festo Automation Suite, especially deployments that include CODESYS Control Runtime versions earlier than 3.5.17.0. OT operators, system integrators, and asset owners responsible for industrial automation engineering workstations or runtime environments should review exposure and update paths.

Technical summary

The flaw is an improper input validation problem in CODESYS Control Runtime before 3.5.17.0. CISA’s advisory states that crafted communication packets can alter router addressing behavior and may re-route, add, remove, or change low-level communication packages. The source material associates affected Festo Automation Suite releases with bundled CODESYS components, including installations below 2.8.0.138 with CODESYS Development System 3.0 or 3.5.16.10.

Defensive priority

High. The issue is network-reachable in the CVSS vector, requires no privileges or user interaction, and affects industrial automation software where routing or communication-path manipulation can disrupt operations. Prioritize inventory, version verification, and upgrade planning for any exposed or operationally critical deployments.

Recommended defensive actions

• Inventory all Festo Automation Suite installations and identify whether CODESYS is bundled or separately installed.
• Upgrade to Festo Automation Suite 2.8.0.138 or later where applicable.
• Update CODESYS Control Runtime to a patched version at or above 3.5.17.0 using the official CODESYS update path.
• Follow the vendor installation and update instructions to ensure the correct security fixes are applied.
• Monitor Festo and CODESYS security advisories and apply updates promptly.
• Use ICS network segmentation and other defense-in-depth controls to reduce the impact of unauthorized traffic reaching industrial automation systems.

Evidence notes

The CVE description in the source corpus states that CODESYS Control Runtime system before 3.5.17.0 has improper input validation and that crafted packets may alter routing and low-level communications. The CISA CSAF source item is the primary evidence base and was republished on 2026-03-17 as a CISA republication of Festo SE & Co. KG advisory FSA-202601. The vendor metadata in the prompt is low-confidence and marked for review, so product attribution should be treated carefully and anchored to the advisory text rather than the label alone.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.