This vulnerability involves improper validation of specified quantity in input (CWE-1284) within the IEC 61850 communication stack used by ABB AC800M (System 800xA) and related products. An attacker with network access can exploit this by sending crafted IEC 61850 packets that force PM 877, CI850, and CI868 modules into fault mode or cause unavailability of S+ Operations 61850 connectivity, leading to denial of service. The issue affects multiple product versions as listed, but the System 800xA IEC61850 Connect component is not affected. The vulnerability has a CVSS 4.0 base score of 7.1, indicating high severity, with attack vector being adjacent network and no privileges or user interaction required.

Successful exploitation results in denial of service of the IEC 61850 communication interfaces on affected modules, disrupting 61850 connectivity. This does not affect the overall availability or functionality of the S+ Operations node beyond the communication function. There are no reports of active exploitation in the wild.

Patch status is not yet confirmed—check the vendor advisory for current remediation guidance. Since no official fix or temporary mitigation is documented, organizations should restrict access to IEC 61850 networks to trusted entities only and monitor for unusual communication patterns targeting the affected modules. No vendor advisory indicating 'no action required' or existing mitigation is provided.