Affected: MZ Automation GmbH libiec61850

The MMS BER decoder contains a boundary-handling flaw in the processing of certain fields within confirmed-request messages. When a crafted BER-encoded element is received over an established MMS session (TCP port 102), the decoder may advance its internal read position incorrectly, leading to a heap out-of-bounds read. This condition causes the MMS handling process to terminate unexpectedly, resulting in a denial-of-service.