diff --git a/include/nuttx/sched.h b/include/nuttx/sched.h
index c00a5b825e..8d076011ed 100644
--- a/include/nuttx/sched.h
+++ b/include/nuttx/sched.h
@@ -1245,13 +1245,17 @@ int nxsched_setaffinity(pid_t pid, size_t cpusetsize,
  *   Report information about a thread's stack allocation.
  *
  * Input Parameters:
- *   pid_t     - Identifies the thread to query.  Zero is interpreted as the
+ *   pid       - Identifies the thread to query.  Zero is interpreted as the
  *               the calling thread
  *   stackinfo - User-provided location to return the stack information.
  *
  * Returned Value:
  *   Zero (OK) if successful.  Otherwise, a negated errno value is returned.
  *
+ *     -ENOENT  Returned if pid does not refer to an active task
+ *     -EACCES  The calling thread does not have privileges to access the
+ *              stack of the thread associated with the pid.
+ *
  ********************************************************************************/
 
 int sched_get_stackinfo(pid_t pid, FAR struct stackinfo_s *stackinfo);
diff --git a/sched/sched/sched_get_stackinfo.c b/sched/sched/sched_get_stackinfo.c
index 4803fb7fa2..2ce750268d 100644
--- a/sched/sched/sched_get_stackinfo.c
+++ b/sched/sched/sched_get_stackinfo.c
@@ -41,37 +41,65 @@
  *   Report information about a thread's stack allocation.
  *
  * Input Parameters:
- *   pid_t     - Identifies the thread to query.  Zero is interpreted as the
+ *   pid       - Identifies the thread to query.  Zero is interpreted as the
  *               the calling thread
  *   stackinfo - User-provided location to return the stack information.
  *
  * Returned Value:
  *   Zero (OK) if successful.  Otherwise, a negated errno value is returned.
  *
+ *     -ENOENT  Returned if pid does not refer to an active task
+ *     -EACCES  The calling thread does not have privileges to access the
+ *              stack of the thread associated with the pid.
+ *
  ****************************************************************************/
 
 int sched_get_stackinfo(pid_t pid, FAR struct stackinfo_s *stackinfo)
 {
-  FAR struct tcb_s *tcb;
+  FAR struct tcb_s *rtcb = this_task();  /* TCB of running task */
+  FAR struct tcb_s *qtcb;                /* TCB of queried task */
 
-  DEBUGASSERT(stackinfo != NULL);
+  DEBUGASSERT(rtcb != NULL && stackinfo != NULL);
+
+  /*  Pid of 0 means that we are querying ourself */
 
   if (pid == 0)
     {
-      tcb = this_task();
-      DEBUGASSERT(tcb != NULL);
+      /* We can always query ourself */
+
+      qtcb = rtcb;
     }
   else
     {
-      tcb = sched_gettcb(pid);
-      if (tcb == NULL)
+      /* Get the task to be queried */
+
+      qtcb = sched_gettcb(pid);
+      if (qtcb == NULL)
         {
           return -ENOENT;
         }
+
+      /* A kernel thread can query any other thread.  Application threads
+       * can only query application threads in the same task group.
+       */
+
+      if ((rtcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_KERNEL)
+        {
+          /* It is an application thread.  It is permitted to query
+           * only threads within the same task group.  It is not permitted
+           * to peek into the stacks of either kernel threads or other
+           * applications tasks.
+           */
+
+          if (rtcb->group != qtcb->group)
+            {
+              return -EACCES;
+            }
+        }
     }
 
-  stackinfo->adj_stack_size  = tcb->adj_stack_size;
-  stackinfo->stack_alloc_ptr = tcb->stack_alloc_ptr;
-  stackinfo->adj_stack_ptr   = tcb->adj_stack_ptr;
+  stackinfo->adj_stack_size  = qtcb->adj_stack_size;
+  stackinfo->stack_alloc_ptr = qtcb->stack_alloc_ptr;
+  stackinfo->adj_stack_ptr   = qtcb->adj_stack_ptr;
   return OK;
 }