CVE-2026-66720 MZ Automation libiec61850 Out-of-bounds Read
A remote attacker can crash the application by sending a malformed GOOSE frame with an undersized timestamp, causing a denial of service.
- 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-2026-66720?
CVE-2026-66720 is a high-severity denial of service 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 subscriber component improperly validates the UTC timestamp field in unauthenticated IEC 61850 GOOSE (EtherType 0x88B8) Layer-2 multicast messages. A specially crafted GOOSE frame containing an undersized timestamp field can trigger a heap out-of-bounds read during message processing, causing the process to crash and resulting in a denial-of-service condition.
Weakness: CWE-125
Which versions are affected by CVE-2026-66720?
How do I fix CVE-2026-66720?
No fix has been published for CVE-2026-66720 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-2026-66720 being exploited?
There is no known exploitation of CVE-2026-66720 in the wild and no public exploit code.
Sources
Also known as GHSA-r4hv-9qm7-gp9j.