CVE-2026-3509: CODESYS Control Audit Log Format String DoS

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-24 · updated 2026-06-17
Weakness: CWE-134

Description

An unauthenticated remote attacker may be able to control the format string of messages processed by the Audit Log of the CODESYS Control runtime system, potentially resulting in a denial‑of‑service (DoS) condition.

Affected products

CODESYS Control for BeagleBone SL: from 4.1.0.0 before 4.21.0.0 — fixed in 4.21.0.0
CODESYS Control for emPC-A/iMX6 SL: from 4.1.0.0 before 4.21.0.0 — fixed in 4.21.0.0
CODESYS Control for IOT2000 SL: from 4.1.0.0 before 4.21.0.0 — fixed in 4.21.0.0
CODESYS Control for Linux ARM SL: from 4.1.0.0 before 4.21.0.0 — fixed in 4.21.0.0
CODESYS Control for Linux SL: from 4.1.0.0 before 4.21.0.0 — fixed in 4.21.0.0
CODESYS Control for PFC100 SL: from 4.1.0.0 before 4.21.0.0 — fixed in 4.21.0.0
CODESYS Control for PFC200 SL: from 4.1.0.0 before 4.21.0.0 — fixed in 4.21.0.0
CODESYS Control for PLCnext SL: from 4.1.0.0 before 4.21.0.0 — fixed in 4.21.0.0
CODESYS Control for Raspberry Pi SL: from 4.1.0.0 before 4.21.0.0 — fixed in 4.21.0.0
CODESYS Control for WAGO Touch Panels 600 SL: from 4.1.0.0 before 4.21.0.0 — fixed in 4.21.0.0
CODESYS Control RTE (for Beckhoff CX) SL: from 3.5.17.0 before 3.5.22.0 — fixed in 3.5.22.0
CODESYS Control RTE (SL): from 3.5.17.0 before 3.5.22.0 — fixed in 3.5.22.0
CODESYS Control Win (SL): from 3.5.17.0 before 3.5.22.0 — fixed in 3.5.22.0
CODESYS Runtime Toolkit: from 3.5.17.0 before 3.5.22.0 — fixed in 3.5.22.0
CODESYS Virtual Control SL: from 4.1.0.0 before 4.21.0.0 — fixed in 4.21.0.0

How to fix

Upgrade to a fixed version: CODESYS Control for BeagleBone SL 4.21.0.0; CODESYS Control for emPC-A/iMX6 SL 4.21.0.0; CODESYS Control for IOT2000 SL 4.21.0.0; CODESYS Control for Linux ARM SL 4.21.0.0; CODESYS Control for Linux SL 4.21.0.0; CODESYS Control for PFC100 SL 4.21.0.0; CODESYS Control for PFC200 SL 4.21.0.0; CODESYS Control for PLCnext SL 4.21.0.0; CODESYS Control for Raspberry Pi SL 4.21.0.0; CODESYS Control for WAGO Touch Panels 600 SL 4.21.0.0; CODESYS Control RTE (for Beckhoff CX) SL 3.5.22.0; CODESYS Control RTE (SL) 3.5.22.0. Check the vendor advisory for mitigations.

References

https://certvde.com/de/advisories/VDE-2026-018

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