Fix a potential problem in JavaTimeModule._findFactory()

datetime/src/main/java/com/fasterxml/jackson/datatype/jsr310/JavaTimeModule.java

@@ -266,21 +266,27 @@ protected AnnotatedMethod _findFactory(AnnotatedClass cls, String name, Class<?>
     {
         final int argCount = argTypes.length;
         for (AnnotatedMethod method : cls.getFactoryMethods()) {
-            if (!name.equals(method.getName())
-                    || (method.getParameterCount() != argCount)) {
-                continue;
+            if (name.equals(method.getName())
+                    && (method.getParameterCount() == argCount)
+                    && _allArgTypesMatch(argTypes, method)) {
+                    return method;
             }
-            for (int i = 0; i < argCount; ++i) {
-                Class<?> argType = method.getParameter(i).getRawType();
-                if (!argType.isAssignableFrom(argTypes[i])) {
-                    continue;
-                }
-            }
-            return method;
         }
         return null;
     }
 
+    // @since 2.21
+    private boolean _allArgTypesMatch(Class<?>[] expectedArgTypes, AnnotatedMethod method)
+    {
+        for (int i = 0, len = expectedArgTypes.length; i < len; ++i) {
+            Class<?> argType = method.getParameter(i).getRawType();
+            if (!argType.isAssignableFrom(expectedArgTypes[i])) {
+                return false;
+            }
+        }
+        return true;
+    }
+
     /**
      * Container for serializers, with one tweak; specific lookup we need to deal
      * with specific {@code TemporalAdjuster} closure subtypes.

release-notes/CREDITS-2.x

@@ -222,11 +222,15 @@ Joey Muia (@jmuia)
   `WRITE_DURATIONS_AS_TIMESTAMPS` enabled
   (2.19.0)
 
-Henning Pöttker (@ hpoettker)
+Henning Pöttker (@hpoettker)
  * Contributed #342: Lenient deserialization of `LocalDate` is not time-zone aware
   (2.19.0)
 
 Boleslav Bobcik (@bbobcik)
  * Reported, contributed fix for #364: Deserialization of Month in ONE_BASED_MONTHS
    mode fails for value "12"
   (2.19.0)
+
+Albert Lovers (@AlbertLovers)
+ * Reported, contributed fix for #381: Fix a potential problem in `JavaTimeModule._findFactory()`
+  (2.21.0)

release-notes/VERSION-2.x

@@ -17,8 +17,8 @@ Modules:
 #376: Allow specifying custom `DateTimeFormatter` for `OffsetDateTime` ser/deser
   (new constructors?)
  (requested by @ZIRAKrezovic)
-
-No changes since 2.20
+#381: Fix a potential problem in `JavaTimeModule._findFactory()`
+ (reported, fix by, Albert L)
 
 2.20.1 (30-Oct-2025)
 2.20.0 (28-Aug-2025)