From 90818bad427b5fc5d5a5255049fb17d10afefcae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Kothe?= <kothe65@gmail.com>
Date: Tue, 2 Sep 2025 21:45:07 -0300
Subject: [PATCH] BUG: fix memory leak in JSON datetime serialization (#62217)

---
 pandas/_libs/src/vendored/ujson/python/objToJSON.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/_libs/src/vendored/ujson/python/objToJSON.c b/pandas/_libs/src/vendored/ujson/python/objToJSON.c
index 5f35860c59cb7..4c89bd9540312 100644
--- a/pandas/_libs/src/vendored/ujson/python/objToJSON.c
+++ b/pandas/_libs/src/vendored/ujson/python/objToJSON.c
@@ -346,7 +346,8 @@ static char *PyDateTimeToIsoCallback(JSOBJ obj, JSONTypeContext *tc,
   }
 
   NPY_DATETIMEUNIT base = ((PyObjectEncoder *)tc->encoder)->datetimeUnit;
-  return PyDateTimeToIso(obj, base, len);
+  GET_TC(tc)->cStr = PyDateTimeToIso(obj, base, len);
+  return GET_TC(tc)->cStr;
 }
 
 static char *PyTimeToJSON(JSOBJ _obj, JSONTypeContext *tc, size_t *outLen) {