CVE-2026-3509 CODESYS Control Audit Log Format String DoS
Unauthenticated remote attackers can cause denial of service in CODESYS Control runtime systems by manipulating audit log format strings.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-3509?
CVE-2026-3509 is a high-severity denial of service vulnerability in CODESYS Control RTE (SL), published on 24 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-134
Which versions are affected by CVE-2026-3509?
How do I fix CVE-2026-3509?
No fix has been published for CVE-2026-3509 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-3509 being exploited?
There is no known exploitation of CVE-2026-3509 in the wild and no public exploit code.
Sources
Also known as GHSA-34rr-qp2j-p4q7.