The GOOSE payload parser in MZ Automation's libiec61850 contains a boundary handling flaw that allows a controlled inner element length to exceed its enclosing length, resulting in an out-of-bounds read of one byte. This flaw causes the subscriber process to terminate reliably, leading to a denial‑of‑service condition without granting the attacker any other privileges. The weakness is associated with CWE‑125, an out‑of‑bounds read.

The vulnerability affects MZ Automation GmbH's libiec61850 library. Users should upgrade to version 1.6.2 or later to obtain the fix. No other vendors or product versions are listed as affected.

The CVSS score of 7.1 indicates a high severity. EPSS score is < 1%, and the vulnerability is not listed in CISA's KEV catalog. The attack vector is a single unauthenticated Layer 2 multicast frame sent on the process bus, which an attacker with access to the network segment hosting the control system can deliver. This makes the exploit realistic for attackers with network reach into the process bus or those who can intercept or inject packets locally. The impact is limited to denial of service of the subscriber process, but repeated crashes can disrupt critical industrial control operations.