Seaborne, who can play centre-back or left-back, has only made three appearances for the Saints this season, all of them coming in the Capital One Cup.
The 25-year-old is due to stay at the Valley until 8 December and could find himself thrust into early first-team action on Sunday at Bristol City with only one fit full-back in the squad at the moment.
Cedric Evina and Lawrie Wilson recently joined Rhoys Wiggins in the treatment room, leaving Chris Solly to man the fort with stand-ins Salim Kerkar and Michael Morrison.
Wiggins is recovering from two fractured metatarsals, while fellow left-sider Evina suffered a knee injury in training last week and versatile right-back Wilson injured the quad muscle in his left thigh during the defeat to Middlesbrough at the start of the month.
Barnstaple-born Seaborne was a trainee at Exeter and went on to skipper the Grecians and played a part - alongside Charlton's Matty Taylor - as the club soared from the Conference to League One in successive seasons.
He has only just returned to action after suffering serious injuries in an attack outside a Southampton nightclub in September 2011.