diff --git a/tools/acrn-manager/acrnctl.c b/tools/acrn-manager/acrnctl.c
index ccc60eed2..5e0be864a 100644
--- a/tools/acrn-manager/acrnctl.c
+++ b/tools/acrn-manager/acrnctl.c
@@ -145,6 +145,7 @@ static void vmm_update(void)
 	char *vmname;
 	char *pvmname = NULL;
 	struct vmm_struct *s;
+	size_t len = sizeof(cmd_out);
 
 	snprintf(cmd, sizeof(cmd),
 		 "find %s/add/ -name \"*.sh\" | "
@@ -152,6 +153,9 @@ static void vmm_update(void)
 		 "sed \"s/.sh//g\"", ACRNCTL_OPT_ROOT);
 	shell_cmd(cmd, cmd_out, sizeof(cmd_out));
 
+	/* Properly null-terminate cmd_out */
+	cmd_out[len - 1] = '\0';
+
 	vmname = strtok_r(cmd_out, "\n", &pvmname);
 	while (vmname) {
 		s = vmm_list_add(vmname);
@@ -169,6 +173,9 @@ static void vmm_update(void)
 		 "sed \"s/-monitor.socket//g\"", ACRN_DM_SOCK_ROOT);
 	shell_cmd(cmd, cmd_out, sizeof(cmd_out));
 
+	/* Properly null-terminate cmd_out */
+	cmd_out[len - 1] = '\0';
+
 	vmname = strtok_r(cmd_out, "\n", &pvmname);
 	while (vmname) {
 		s = vmm_find(vmname);
@@ -314,6 +321,7 @@ static int acrnctl_do_add(int argc, char *argv[])
 	int p, i;
 	char cmd_out[256];
 	char vmname[128];
+	size_t len = sizeof(cmd_out);
 
 	if (argc < 2) {
 		acrnctl_add_help();
@@ -375,6 +383,9 @@ static int acrnctl_do_add(int argc, char *argv[])
 
 	find_acrn_dm = 0;
 
+	/* Properly null-terminate buf */
+	buf[MAX_FILE_SIZE - 1] = '\0';
+
 	line = strtok_r(buf, "\n", &line_p);
 	while (line) {
 		word_p = NULL;
@@ -423,6 +434,10 @@ static int acrnctl_do_add(int argc, char *argv[])
 		ret = -1;
 		snprintf(cmd, sizeof(cmd), "cat ./%s.result", argv[1]);
 		shell_cmd(cmd, cmd_out, sizeof(cmd_out));
+
+		/* Properly null-terminate cmd_out */
+		cmd_out[len - 1] = '\0';
+
 		printf("%s can't reach acrn-dm, "
 		       "please try again when you make sure it can launch an UOS\n"
 		       "result:\n%s\n", argv[1], cmd_out);