diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index ba2844d..3735424 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -1826,6 +1826,10 @@
         with self.assertRaises(ValueError):
             subprocess.check_call(ZERO_RETURN_CMD, user=-1)
 
+        with self.assertRaises(OverflowError):
+            subprocess.check_call(ZERO_RETURN_CMD,
+                                  cwd=os.curdir, env=os.environ, user=2**64)
+
         if pwd is None and name_uid is not None:
             with self.assertRaises(ValueError):
                 subprocess.check_call(ZERO_RETURN_CMD, user=name_uid)
@@ -1869,6 +1873,10 @@
         with self.assertRaises(ValueError):
             subprocess.check_call(ZERO_RETURN_CMD, group=-1)
 
+        with self.assertRaises(OverflowError):
+            subprocess.check_call(ZERO_RETURN_CMD,
+                                  cwd=os.curdir, env=os.environ, group=2**64)
+
         if grp is None:
             with self.assertRaises(ValueError):
                 subprocess.check_call(ZERO_RETURN_CMD, group=name_group)
@@ -1917,6 +1925,11 @@
         with self.assertRaises(ValueError):
             subprocess.check_call(ZERO_RETURN_CMD, extra_groups=[-1])
 
+        with self.assertRaises(ValueError):
+            subprocess.check_call(ZERO_RETURN_CMD,
+                                  cwd=os.curdir, env=os.environ,
+                                  extra_groups=[2**64])
+
         if grp is None:
             with self.assertRaises(ValueError):
                 subprocess.check_call(ZERO_RETURN_CMD,
diff --git a/Misc/NEWS.d/next/Library/2020-10-25-19-25-02.bpo-42146.6A8uvS.rst b/Misc/NEWS.d/next/Library/2020-10-25-19-25-02.bpo-42146.6A8uvS.rst
new file mode 100644
index 0000000..0418098
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-10-25-19-25-02.bpo-42146.6A8uvS.rst
@@ -0,0 +1,2 @@
+Fix memory leak in :func:`subprocess.Popen` in case an uid (gid) specified in
+`user` (`group`, `extra_groups`) overflows `uid_t` (`gid_t`).
diff --git a/Modules/_posixsubprocess.c b/Modules/_posixsubprocess.c
index 5d1691a..5356417 100644
--- a/Modules/_posixsubprocess.c
+++ b/Modules/_posixsubprocess.c
@@ -626,7 +626,7 @@
     uid_t uid;
     gid_t gid, *groups = NULL;
     int child_umask;
-    PyObject *cwd_obj, *cwd_obj2;
+    PyObject *cwd_obj, *cwd_obj2 = NULL;
     const char *cwd;
     pid_t pid;
     int need_to_reenable_gc = 0;
@@ -748,7 +748,6 @@
         cwd = PyBytes_AsString(cwd_obj2);
     } else {
         cwd = NULL;
-        cwd_obj2 = NULL;
     }
 
     if (groups_list != Py_None) {
@@ -908,6 +907,7 @@
     return PyLong_FromPid(pid);
 
 cleanup:
+    Py_XDECREF(cwd_obj2);
     if (envp)
         _Py_FreeCharPArray(envp);
     if (argv)