Upstream report: https://bitbucket.org/tildeslash/monit/issues/867/invalid-use-of-vfork-in-command_execute

diff --git a/libmonit/src/system/Command.c b/libmonit/src/system/Command.c
index a17fde4..2c75fe4 100644
--- a/libmonit/src/system/Command.c
+++ b/libmonit/src/system/Command.c
@@ -497,7 +497,7 @@ Process_T Command_execute(T C) {
         Process_T P = _Process_new();
         int descriptors = System_getDescriptorsGuarded();
         _createPipes(P);
-        if ((P->pid = vfork()) < 0) {
+        if ((P->pid = fork()) < 0) {
                 ERROR("Command: fork failed -- %s\n", System_getLastError());
                 Process_free(&P);
                 return NULL;