diff --git a/ext/ldap/ldap.c b/ext/ldap/ldap.c
index f0dd3ccb4c4..ede60a29846 100644
--- a/ext/ldap/ldap.c
+++ b/ext/ldap/ldap.c
@@ -2181,6 +2181,8 @@ static void php_ldap_do_modify(INTERNAL_FUNCTION_PARAMETERS, int oper, int ext)
 			convert_to_string(value);
 			if (EG(exception)) {
 				RETVAL_FALSE;
+				num_berval[i] = 0;
+				num_attribs = i + 1;
 				goto cleanup;
 			}
 			ldap_mods[i]->mod_bvalues[0] = (struct berval *) emalloc (sizeof(struct berval));
@@ -2197,6 +2199,8 @@ static void php_ldap_do_modify(INTERNAL_FUNCTION_PARAMETERS, int oper, int ext)
 				}
 				convert_to_string(ivalue);
 				if (EG(exception)) {
+					num_berval[i] = j;
+					num_attribs = i + 1;
 					RETVAL_FALSE;
 					goto cleanup;
 				}
diff --git a/ext/ldap/tests/gh16132-1.phpt b/ext/ldap/tests/gh16132-1.phpt
new file mode 100644
index 00000000000..1979796446d
--- /dev/null
+++ b/ext/ldap/tests/gh16132-1.phpt
@@ -0,0 +1,28 @@
+--TEST--
+Bug GH-16132: Attempting to free pointer not allocated by ZMM
+--EXTENSIONS--
+ldap
+--FILE--
+<?php
+
+/* ldap_add(_ext)(), ldap_mod_replace(_ext)(), ldap_mod_add(_ext)(), and ldap_mod_del(_ext)() share an underlying C function */
+/* We are assuming 3333 is not connectable */
+$ldap = ldap_connect('ldap://127.0.0.1:3333');
+$valid_dn = "cn=userA,something";
+
+$dict_key_value_not_string = [
+    'attribute1' => new stdClass(),
+    'attribute2' => [
+        'value1',
+        'value2',
+    ],
+];
+try {
+    var_dump(ldap_add($ldap, $valid_dn, $dict_key_value_not_string));
+} catch (Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+
+?>
+--EXPECT--
+Error: Object of class stdClass could not be converted to string
diff --git a/ext/ldap/tests/gh16132-2.phpt b/ext/ldap/tests/gh16132-2.phpt
new file mode 100644
index 00000000000..eaf3bd67dfc
--- /dev/null
+++ b/ext/ldap/tests/gh16132-2.phpt
@@ -0,0 +1,28 @@
+--TEST--
+Bug GH-16132: Attempting to free pointer not allocated by ZMM
+--EXTENSIONS--
+ldap
+--FILE--
+<?php
+
+/* ldap_add(_ext)(), ldap_mod_replace(_ext)(), ldap_mod_add(_ext)(), and ldap_mod_del(_ext)() share an underlying C function */
+/* We are assuming 3333 is not connectable */
+$ldap = ldap_connect('ldap://127.0.0.1:3333');
+$valid_dn = "cn=userA,something";
+
+$dict_key_multi_value_not_list_of_strings2 = [
+    'attribute1' => 'value',
+    'attribute2' => [
+        'value1',
+        new stdClass(),
+    ],
+];
+try {
+    var_dump(ldap_add($ldap, $valid_dn, $dict_key_multi_value_not_list_of_strings2));
+} catch (Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+
+?>
+--EXPECT--
+Error: Object of class stdClass could not be converted to string