diff --git a/.changeset/five-birds-check.md b/.changeset/five-birds-check.md
new file mode 100644
index 0000000000..edf46bff53
--- /dev/null
+++ b/.changeset/five-birds-check.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: widen ownership upon property access if necessary
diff --git a/packages/svelte/src/internal/client/proxy.js b/packages/svelte/src/internal/client/proxy.js
index 48d6df4d30..13367ec2fd 100644
--- a/packages/svelte/src/internal/client/proxy.js
+++ b/packages/svelte/src/internal/client/proxy.js
@@ -131,6 +131,22 @@ export function proxy(value, parent = null, prev) {
 
 			if (s !== undefined) {
 				var v = get(s);
+
+				// In case of something like `foo = bar.map(...)`, foo would have ownership
+				// of the array itself, while the individual items would have ownership
+				// of the component that created the proxy. That means if we later do
+				// `foo[0].baz = 42`, we could get a false-positive ownership violation,
+				// since the two proxies are not connected to each other via the parent
+				// relationship. For this reason, we need to widen the ownership of the
+				// children upon access when we detect they are not connected.
+				if (DEV) {
+					/** @type {ProxyMetadata | undefined} */
+					var prop_metadata = v?.[STATE_SYMBOL_METADATA];
+					if (prop_metadata && prop_metadata?.parent !== metadata) {
+						widen_ownership(metadata, prop_metadata);
+					}
+				}
+
 				return v === UNINITIALIZED ? undefined : v;
 			}
 
diff --git a/packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-7/Component1.svelte b/packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-7/Component1.svelte
new file mode 100644
index 0000000000..1db07ddbd0
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-7/Component1.svelte
@@ -0,0 +1,13 @@
+<script>
+	import Component2 from './Component2.svelte';
+
+	let { rows = $bindable([]) } = $props();
+
+	let rows2 = $state([]);
+
+	$effect(() => {
+		rows2 = rows.slice();
+	});
+</script>
+
+<Component2 bind:rows={rows2} />
diff --git a/packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-7/Component2.svelte b/packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-7/Component2.svelte
new file mode 100644
index 0000000000..8d63b9e9a9
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-7/Component2.svelte
@@ -0,0 +1,7 @@
+<script>
+	let { rows = $bindable([]) } = $props();
+</script>
+
+{#if rows.length}
+	<input type="checkbox" bind:checked={rows[0].check} />
+{/if}
diff --git a/packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-7/_config.js b/packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-7/_config.js
new file mode 100644
index 0000000000..e766a946d0
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-7/_config.js
@@ -0,0 +1,22 @@
+import { flushSync } from 'svelte';
+import { ok, test } from '../../test';
+
+// Tests that proxies widen ownership correctly even if not directly connected to each other
+export default test({
+	compileOptions: {
+		dev: true
+	},
+
+	test({ assert, target, warnings }) {
+		const input = target.querySelector('input');
+		ok(input);
+
+		input.checked = true;
+		input.dispatchEvent(new Event('input', { bubbles: true }));
+		flushSync();
+
+		assert.deepEqual(warnings, []);
+	},
+
+	warnings: []
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-7/main.svelte b/packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-7/main.svelte
new file mode 100644
index 0000000000..60a9b19a05
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/non-local-mutation-with-binding-7/main.svelte
@@ -0,0 +1,7 @@
+<script>
+	import Component1 from './Component1.svelte';
+
+	let rows = $state([{}]);
+</script>
+
+<Component1 bind:rows />