A cylinder lock for mounting on a panel, comprising: - a first lock housing provided with a first lock cylinder which is received in the first lock housing in a manner rotatable around a central axis and which is operable from a first side of the panel; - a rotatable carrier which is provided with a carrier cam and which, viewed from the first side, is located behind the first lock housing, in line with the first lock housing; and - a blocking assembly (20, 22, 28, 30, 32, 36) provided between the first lock housing and the carrier, wherein the blocking assembly (20, 22, 28, 30, 32, 36) comprises a rotatable blocking disk and a blocking element, wherein the blocking disk is nonrotatably connected with the first lock cylinder and the carrier, and is configured for transmitting a rotation of the first lock cylinder to the carrier, wherein the blocking element in normal use is in a release position, in which the blocking element is clear of the blocking disk, wherein the blocking element is in a blocking position if the first lock housing has been removed from the cylinder lock, in which blocking position the blocking element blocks rotation of the blocking disk and whereby the blocking disk screens the carrier off from access from the first side of the panel, wherein the blocking element is a blocking pin which by means of a biasing element is urged in the direction of the blocking disk, wherein the blocking pin is provided with a cam having an oblique surface, which is located obliquely with respect to the urging direction of the biasing element, wherein the blocking assembly (20, 22, 28, 30, 32, 36) further comprises a retaining element which is clamped between the oblique surface of the cam and the first lock housing and hinders a movement of the blocking pin in the direction of the blocking disk, wherein the biasing element comprises a spring, characterized in that the blocking pin is provided with an open blocking pin chamber at an end of the blocking pin remote from the blocking disk, wherein the spring at least in part extends in the blocking pin chamber, wherein in the release position in blocking pin chamber a ring is received which surrounds the spring, wherein, when the blocking pin is in the blocking position, the ring has moved out of the blocking pin chamber and hinders that the blocking pin can be brought from the blocking position to the release position. - a first lock housing provided with a first lock cylinder which is received in the first lock housing in a manner rotatable around a central axis and which is operable from a first side of the panel; - a rotatable carrier which is provided with a carrier cam and which, viewed from the first side, is located behind the first lock housing, in line with the first lock housing; and - a blocking assembly (20, 22, 28, 30, 32, 36) provided between the first lock housing and the carrier, wherein the blocking assembly (20, 22, 28, 30, 32, 36) comprises a rotatable blocking disk and a blocking element, wherein the blocking disk is nonrotatably connected with the first lock cylinder and the carrier, and is configured for transmitting a rotation of the first lock cylinder to the carrier, wherein the blocking element in normal use is in a release position, in which the blocking element is clear of the blocking disk, wherein the blocking element is in a blocking position if the first lock housing has been removed from the cylinder lock, in which blocking position the blocking element blocks rotation of the blocking disk and whereby the blocking disk screens the carrier off from access from the first side of the panel, wherein the blocking element is a blocking pin which by means of a biasing element is urged in the direction of the blocking disk, wherein the blocking pin is provided with a cam having an oblique surface, which is located obliquely with respect to the urging direction of the biasing element, wherein the blocking assembly (20, 22, 28, 30, 32, 36) further comprises a retaining element which is clamped between the oblique surface of the cam and the first lock housing and hinders a movement of the blocking pin in the direction of the blocking disk, wherein the biasing element comprises a spring, characterized in that the blocking pin is provided with an open blocking pin chamber at an end of the blocking pin remote from the blocking disk, wherein the spring at least in part extends in the blocking pin chamber, wherein in the release position in blocking pin chamber a ring is received which surrounds the spring, wherein, when the blocking pin is in the blocking position, the ring has moved out of the blocking pin chamber and hinders that the blocking pin can be brought from the blocking position to the release position.