diff --git a/deps/v8/include/v8-version.h b/deps/v8/include/v8-version.h
index f16596a58fa667..e769d42101e818 100644
--- a/deps/v8/include/v8-version.h
+++ b/deps/v8/include/v8-version.h
@@ -11,7 +11,7 @@
 #define V8_MAJOR_VERSION 12
 #define V8_MINOR_VERSION 4
 #define V8_BUILD_NUMBER 254
-#define V8_PATCH_LEVEL 14
+#define V8_PATCH_LEVEL 17
 
 // Use 1 for candidates and 0 otherwise.
 // (Boolean macro values are not supported by all preprocessors.)
diff --git a/deps/v8/infra/testing/builders.pyl b/deps/v8/infra/testing/builders.pyl
index 2aca712ca73f8a..7655763cab411c 100644
--- a/deps/v8/infra/testing/builders.pyl
+++ b/deps/v8/infra/testing/builders.pyl
@@ -962,7 +962,7 @@
   'v8_mac64_asan_rel': {
     'swarming_dimensions' : {
       'cpu': 'x86-64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
     },
     'tests': [
       {'name': 'v8testing', 'shards': 8},
@@ -971,7 +971,7 @@
   'v8_mac64_dbg': {
     'swarming_dimensions' : {
       'cpu': 'x86-64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
     },
     'tests': [
       {'name': 'mozilla'},
@@ -984,7 +984,7 @@
   'v8_mac_arm64_gc_stress_dbg': {
     'swarming_dimensions' : {
       'cpu': 'arm64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
     },
     'tests': [
       {'name': 'd8testing', 'test_args': ['--gc-stress'], 'shards': 3},
@@ -993,7 +993,7 @@
   'v8_mac64_noopt_dbg': {
     'swarming_dimensions' : {
       'cpu': 'x86-64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
     },
     'tests': [
       {'name': 'v8testing', 'shards': 6},
@@ -1002,7 +1002,7 @@
   'v8_mac64_rel': {
     'swarming_dimensions' : {
       'cpu': 'x86-64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
     },
     'tests': [
       {'name': 'mozilla'},
@@ -1015,7 +1015,7 @@
   'v8_mac_arm64_rel': {
     'swarming_dimensions' : {
       'cpu': 'arm64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
       'pool': 'chromium.tests',
     },
     'tests': [
@@ -1031,7 +1031,7 @@
   'v8_mac_arm64_dbg': {
     'swarming_dimensions' : {
       'cpu': 'arm64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
       'pool': 'chromium.tests',
     },
     'tests': [
@@ -1047,7 +1047,7 @@
   'v8_mac_arm64_full_dbg': {
     'swarming_dimensions' : {
       'cpu': 'arm64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
       'pool': 'chromium.tests',
     },
     'tests': [
@@ -1063,7 +1063,7 @@
   'v8_mac_arm64_no_pointer_compression_dbg': {
     'swarming_dimensions' : {
       'cpu': 'arm64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
       'pool': 'chromium.tests',
     },
     'tests': [
@@ -1848,7 +1848,7 @@
   'V8 Mac64': {
     'swarming_dimensions': {
       'cpu': 'x86-64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
     },
     'tests': [
       {'name': 'mozilla'},
@@ -1861,7 +1861,7 @@
   'V8 Mac64 - debug': {
     'swarming_dimensions': {
       'cpu': 'x86-64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
     },
     'tests': [
       {'name': 'mozilla'},
@@ -1874,7 +1874,7 @@
   'V8 Mac64 ASAN': {
     'swarming_dimensions': {
       'cpu': 'x86-64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
     },
     'tests': [
       {'name': 'v8testing', 'shards': 10},
@@ -1883,7 +1883,7 @@
   'V8 Mac - arm64 - gc stress': {
     'swarming_dimensions': {
       'cpu': 'arm64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
     },
     'tests': [
       {'name': 'd8testing', 'test_args': ['--gc-stress'], 'shards': 3},
@@ -1891,7 +1891,7 @@
   },
   'V8 Mac - arm64': {
     'swarming_dimensions' : {
-      'os': 'Mac-13',
+      'os': 'Mac-14',
       'cpu': 'arm64',
       'pool': 'chromium.tests',
     },
@@ -1908,7 +1908,7 @@
   },
   'V8 Mac - arm64 - release': {
     'swarming_dimensions' : {
-      'os': 'Mac-13',
+      'os': 'Mac-14',
       'cpu': 'arm64',
       'pool': 'chromium.tests',
     },
@@ -1925,7 +1925,7 @@
   },
   'V8 Mac - arm64 - debug': {
     'swarming_dimensions' : {
-      'os': 'Mac-13',
+      'os': 'Mac-14',
       'cpu': 'arm64',
       'pool': 'chromium.tests',
     },
@@ -1943,7 +1943,7 @@
   'V8 Mac - arm64 - no pointer compression debug': {
     'swarming_dimensions' : {
       'cpu': 'arm64',
-      'os': 'Mac-13',
+      'os': 'Mac-14',
       'pool': 'chromium.tests',
     },
     'tests': [
diff --git a/deps/v8/src/compiler/access-info.cc b/deps/v8/src/compiler/access-info.cc
index 7cff878839c85c..9d022ba402d7bf 100644
--- a/deps/v8/src/compiler/access-info.cc
+++ b/deps/v8/src/compiler/access-info.cc
@@ -526,6 +526,14 @@ PropertyAccessInfo AccessorAccessInfoHelper(
         Cell::cast(module_namespace->module()->exports()->Lookup(
             isolate, name.object(),
             Smi::ToInt(Object::GetHash(*name.object())))));
+    if (IsAnyStore(access_mode)) {
+      // ES#sec-module-namespace-exotic-objects-set-p-v-receiver
+      // ES#sec-module-namespace-exotic-objects-defineownproperty-p-desc
+      //
+      // Storing to a module namespace object is always an error or a no-op in
+      // JS.
+      return PropertyAccessInfo::Invalid(zone);
+    }
     if (IsTheHole(cell->value(kRelaxedLoad), isolate)) {
       // This module has not been fully initialized yet.
       return PropertyAccessInfo::Invalid(zone);
diff --git a/deps/v8/src/maglev/maglev-graph-builder.cc b/deps/v8/src/maglev/maglev-graph-builder.cc
index 73ead492da3ee5..efcdd6d2028a5e 100644
--- a/deps/v8/src/maglev/maglev-graph-builder.cc
+++ b/deps/v8/src/maglev/maglev-graph-builder.cc
@@ -4001,19 +4001,28 @@ ReduceResult MaglevGraphBuilder::TryBuildPropertyStore(
         access_info.holder().value());
   }
 
-  if (access_info.IsFastAccessorConstant()) {
-    return TryBuildPropertySetterCall(access_info, receiver,
-                                      GetAccumulatorTagged());
-  } else {
-    DCHECK(access_info.IsDataField() || access_info.IsFastDataConstant());
-    ReduceResult res = TryBuildStoreField(access_info, receiver, access_mode);
-    if (res.IsDone()) {
-      RecordKnownProperty(receiver, name,
-                          current_interpreter_frame_.accumulator(),
-                          AccessInfoGuaranteedConst(access_info), access_mode);
-      return res;
+  switch (access_info.kind()) {
+    case compiler::PropertyAccessInfo::kFastAccessorConstant:
+      return TryBuildPropertySetterCall(access_info, receiver,
+                                        GetAccumulatorTagged());
+    case compiler::PropertyAccessInfo::kDataField:
+    case compiler::PropertyAccessInfo::kFastDataConstant: {
+      ReduceResult res = TryBuildStoreField(access_info, receiver, access_mode);
+      if (res.IsDone()) {
+        RecordKnownProperty(
+            receiver, name, current_interpreter_frame_.accumulator(),
+            AccessInfoGuaranteedConst(access_info), access_mode);
+        return res;
+      }
+      return ReduceResult::Fail();
     }
-    return ReduceResult::Fail();
+    case compiler::PropertyAccessInfo::kInvalid:
+    case compiler::PropertyAccessInfo::kNotFound:
+    case compiler::PropertyAccessInfo::kDictionaryProtoDataConstant:
+    case compiler::PropertyAccessInfo::kDictionaryProtoAccessorConstant:
+    case compiler::PropertyAccessInfo::kModuleExport:
+    case compiler::PropertyAccessInfo::kStringLength:
+      UNREACHABLE();
   }
 }
 
diff --git a/deps/v8/src/objects/js-objects.cc b/deps/v8/src/objects/js-objects.cc
index e5a03dff14835e..2f3ab484cdc010 100644
--- a/deps/v8/src/objects/js-objects.cc
+++ b/deps/v8/src/objects/js-objects.cc
@@ -432,9 +432,7 @@ Maybe<bool> JSReceiver::SetOrCopyDataProperties(
       Nothing<bool>());
 
   if (!from->HasFastProperties() && target->HasFastProperties() &&
-      !IsJSGlobalProxy(*target)) {
-    // JSProxy is always in slow-mode.
-    DCHECK(!IsJSProxy(*target));
+      IsJSObject(*target) && !IsJSGlobalProxy(*target)) {
     // Convert to slow properties if we're guaranteed to overflow the number of
     // descriptors.
     int source_length;