CVE-2026-66369 MZ Automation libiec61850 Out-of-bounds Read
An attacker can cause a denial of service in IEC 61850 subscribers by sending a malicious multicast frame that triggers an out-of-bounds read.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-66369?
CVE-2026-66369 is a high-severity memory corruption vulnerability in MZ Automation GmbH libiec61850, published on 30 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
The GOOSE parser contains an off-by-one boundary-handling flaw that can be triggered by a single unauthenticated Layer-2 multicast frame on the process bus. When specific GOOSE message fields are processed, the parser advances its internal buffer position incorrectly, resulting in a heap out-of-bounds read. On affected platforms, this condition reliably terminates the subscriber process and causes a denial-of-service.
Weakness: CWE-125
Which versions are affected by CVE-2026-66369?
How do I fix CVE-2026-66369?
No fix has been published for CVE-2026-66369 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-66369 being exploited?
There is no known exploitation of CVE-2026-66369 in the wild and no public exploit code.
Sources
Also known as GHSA-q8fp-56gr-h5jf.