diff --git a/Misc/NEWS.d/next/Security/2023-01-14-23-51-57.gh-issue-101046.rRu9EP.rst b/Misc/NEWS.d/next/Security/2023-01-14-23-51-57.gh-issue-101046.rRu9EP.rst
new file mode 100644
index 00000000000000..48344f003ab4ca
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2023-01-14-23-51-57.gh-issue-101046.rRu9EP.rst
@@ -0,0 +1,2 @@
+Fix a potential memory leak when :func:`PyMem_Realloc` fails inside
+:func:`_loop0_1_rule`. Patch by Ruili Fang
diff --git a/Parser/parser.c b/Parser/parser.c
index d0bc25927bece6..ae41226ef68903 100644
--- a/Parser/parser.c
+++ b/Parser/parser.c
@@ -23803,7 +23803,8 @@ _loop0_1_rule(Parser *p)
                 _children_capacity *= 2;
                 void **_new_children = PyMem_Realloc(_children, _children_capacity*sizeof(void *));
                 if (!_new_children) {
-                    p->error_indicator = 1;
+                    PyMem_Free(_children);
+                                        p->error_indicator = 1;
                     PyErr_NoMemory();
                     p->level--;
                     return NULL;