Abstract: The present invention relates to a low-vulnerability solid-propellant motor (1) comprising a charge (11) of solid propellant, a heat shield (2) covering the inside of a metal structure with a front end wall (3) and a rear end wall (4) which carries at least one nozzle (10), the said front and rear end walls being fastened to a cylindrical shell (5) having wide apertures which are circumferentially distributed and temporarily sealed by sealing plugs (8). The object of the present invention is to provide a motor which has a simple structure and avoids the use of detection and actuation means for freeing the plugs. The motor according to the invention is such that the sealing plugs (8) are held in the apertures between the heat shield and a composite winding (7) of fibres impregnated in a matrix which surrounds the cylindrical shell (5).