diff --git a/packages/zod/src/v4/core/schemas.ts b/packages/zod/src/v4/core/schemas.ts
index e21879438..9fd1d3ce1 100644
--- a/packages/zod/src/v4/core/schemas.ts
+++ b/packages/zod/src/v4/core/schemas.ts
@@ -1903,6 +1903,8 @@ export const $ZodObjectJIT: core.$constructor<$ZodObject> = /*@__PURE__*/ core.$
     // requires cast because technically $ZodObject doesn't extend
     $ZodObject.init(inst, def);
 
+    const visitedNodes = new Set();
+
     const superParse = inst._zod.parse;
     const _normalized = util.cached(() => normalizeDef(def));
 
@@ -1979,6 +1981,15 @@ export const $ZodObjectJIT: core.$constructor<$ZodObject> = /*@__PURE__*/ core.$
         return payload;
       }
 
+      if (visitedNodes.has(input)) {
+        return {
+          value: input,
+          issues: [],
+        };
+      }
+
+      visitedNodes.add(input);
+
       if (jit && fastEnabled && ctx?.async === false && ctx.jitless !== true) {
         // always synchronous
         if (!fastpass) fastpass = generateFastpass(def.shape);
@@ -1990,6 +2001,8 @@ export const $ZodObjectJIT: core.$constructor<$ZodObject> = /*@__PURE__*/ core.$
 
       return superParse(payload, ctx);
     };
+
+    visitedNodes.clear();
   }
 );
 
diff --git a/packages/zod/src/v4/core/tests/circular-object.test.ts b/packages/zod/src/v4/core/tests/circular-object.test.ts
new file mode 100644
index 000000000..8c1be69eb
--- /dev/null
+++ b/packages/zod/src/v4/core/tests/circular-object.test.ts
@@ -0,0 +1,40 @@
+import { test, expect } from "vitest";
+import * as z from "zod/v4";
+
+test("validates circular objects", () => {
+  const userSchema = z.object({
+    id: z.number(),
+    get posts() {
+      return z.array(postSchema);
+    },
+  });
+
+  const postSchema = z.object({
+    title: z.string(),
+    get author() {
+      return userSchema;
+    },
+  });
+
+  const user = {
+    id: 1,
+    posts: [
+      {
+        title: "First",
+        get author() {
+          return user;
+        },
+      },
+    ],
+  };
+
+  expect(userSchema.parse(user)).toEqual({
+    id: 1,
+    posts: [
+      {
+        title: "First",
+        author: user,
+      },
+    ],
+  });
+});