B787 Captain reported a critical software error resulted in the aircraft performing a premature turn to the ILS approach toward terrain; requiring immediate action by the flight crew to return to course.

Narrative

This report highlights a significant flight safety concern and a general observation from an experienced pilot and Captain Boeing 787.We were cleared on an approach sequence related to Runway ILS X XXL in ZZZZ. Proceeding from ZZZZZ intersection; ZZZZ Approach cleared us to a waypoint a ZZZZZ1 at 3000 feet. We proceeded direct to ZZZZZ1 and configured aircraft and accordance with our descent profile.We briefed the approach to include the recent pilot bulletin; false localizer capture; of premature intercepts to a localizer as we proceeded to intersection ZZZZZ1. Approximately three nautical miles from ZZZZZ1 at 3000 feet while LNAV engaged direct to ZZZZZ1; the approach was armed; localizer and glideslope displayed armed. The aircraft turned to parallel the approach course of Runway XXL. And immediate action was required to return the aircraft to the original heading to intercept ILS X XXL and approach mode re-engaged.ZZZZ Approach Control also noticed the inadvertent and premature turn and advised us to turn right to heading of 120 to re-intercept ILS X XXL. The aircraft was returned to the approach course of ILS XXL via heading select and reengaged the approach on the Mode Control Panel (MCP).The flight continued to destination without further incident.This issue needs the highest attention fast before an equally exhausting crew doesn't make the right corrective flight path choices; and continues along the wrong course of action in mountainous terrain.It is apparent that the B787 software drastically needs to be updated to accommodate different approach criteria's as assigned by ATC. This premature turn to ILS X XXL would have taken us directly into high terrain that exceeds thousands of feet; seriously jeopardizing the safety of flight.