diff --git a/backends/vulkan/runtime/VulkanBackend.cpp b/backends/vulkan/runtime/VulkanBackend.cpp
index 3b18915eae5..716d5aa5bd1 100644
--- a/backends/vulkan/runtime/VulkanBackend.cpp
+++ b/backends/vulkan/runtime/VulkanBackend.cpp
@@ -208,6 +208,7 @@ class GraphBuilder {
   ComputeGraph* compute_graph_;
   VkGraphPtr flatbuffer_;
   const uint8_t* constant_data_;
+  uint64_t constant_data_size_;
   const NamedDataMap* named_data_map_;
   std::vector<FreeableBuffer> loaded_buffers_from_map_;
 
@@ -220,10 +221,12 @@ class GraphBuilder {
       ComputeGraph* compute_graph,
       VkGraphPtr flatbuffer,
       const uint8_t* constant_data,
+      uint64_t constant_data_size,
       const NamedDataMap* named_data_map)
       : compute_graph_(compute_graph),
         flatbuffer_(flatbuffer),
         constant_data_(constant_data),
+        constant_data_size_(constant_data_size),
         named_data_map_(named_data_map),
         loaded_buffers_from_map_(),
         ref_mapping_(),
@@ -298,7 +301,33 @@ class GraphBuilder {
         ref = compute_graph_->add_tensorref(
             dims_vector, dtype, std::move(buffer.get()));
       } else {
-        const uint8_t* tensor_data = constant_data_ + constant_bytes->offset();
+        const uint64_t offset = constant_bytes->offset();
+        VK_CHECK_COND(
+            offset < constant_data_size_,
+            "Constant data offset %lu exceeds constant data size %lu",
+            (unsigned long)offset,
+            (unsigned long)constant_data_size_);
+        // Validate that the tensor's full byte extent fits within the
+        // constant data region. Dims originate from an untrusted flatbuffer,
+        // so use overflow-safe multiplication.
+        const uint64_t max_extent = constant_data_size_ - offset;
+        uint64_t tensor_byte_size = vkapi::element_size(dtype);
+        for (int64_t dim : dims_vector) {
+          const uint64_t udim = static_cast<uint64_t>(dim);
+          VK_CHECK_COND(
+              udim == 0 || tensor_byte_size <= max_extent / udim,
+              "Tensor byte extent at offset %lu exceeds constant data size %lu",
+              (unsigned long)offset,
+              (unsigned long)constant_data_size_);
+          tensor_byte_size *= udim;
+        }
+        VK_CHECK_COND(
+            tensor_byte_size <= max_extent,
+            "Tensor byte size %lu at offset %lu exceeds constant data size %lu",
+            (unsigned long)tensor_byte_size,
+            (unsigned long)offset,
+            (unsigned long)constant_data_size_);
+        const uint8_t* tensor_data = constant_data_ + offset;
         ref = compute_graph_->add_tensorref(dims_vector, dtype, tensor_data);
       }
     } else {
@@ -591,19 +620,25 @@ class VulkanBackend final : public ::executorch::runtime::BackendInterface {
 
   ET_NODISCARD Error compileModel(
       const void* buffer_pointer,
+      size_t buffer_size,
       ComputeGraph* compute_graph,
       const NamedDataMap* named_data_map) const {
     Result<VulkanDelegateHeader> header =
-        VulkanDelegateHeader::parse(buffer_pointer);
+        VulkanDelegateHeader::parse(buffer_pointer, buffer_size);
 
     const uint8_t* flatbuffer_data = nullptr;
     const uint8_t* constant_data = nullptr;
+    uint64_t constant_data_size = 0;
 
     if (header.ok()) {
       const uint8_t* buffer_start =
           reinterpret_cast<const uint8_t*>(buffer_pointer);
       flatbuffer_data = buffer_start + header->flatbuffer_offset;
       constant_data = buffer_start + header->bytes_offset;
+      constant_data_size = header->bytes_size;
+      if (constant_data_size == 0 && buffer_size > header->bytes_offset) {
+        constant_data_size = buffer_size - header->bytes_offset;
+      }
     } else {
       ET_LOG(Error, "VulkanDelegateHeader may be corrupt");
       return header.error();
@@ -616,10 +651,21 @@ class VulkanBackend final : public ::executorch::runtime::BackendInterface {
         flatbuffers::GetBufferIdentifier(flatbuffer_data),
         vkgraph::VkGraphIdentifier());
 
+    // Verify FlatBuffer structural integrity before parsing.
+    flatbuffers::Verifier verifier(flatbuffer_data, header->flatbuffer_size);
+    ET_CHECK_OR_RETURN_ERROR(
+        vkgraph::VerifyVkGraphBuffer(verifier),
+        DelegateInvalidCompatibility,
+        "VkGraph FlatBuffer verification failed");
+
     VkGraphPtr flatbuffer_graph = vkgraph::GetVkGraph(flatbuffer_data);
 
     GraphBuilder builder(
-        compute_graph, flatbuffer_graph, constant_data, named_data_map);
+        compute_graph,
+        flatbuffer_graph,
+        constant_data,
+        constant_data_size,
+        named_data_map);
 
     builder.resolve_layouts();
     builder.build_graph();
@@ -649,7 +695,8 @@ class VulkanBackend final : public ::executorch::runtime::BackendInterface {
     new (compute_graph) ComputeGraph(graph_config);
 
     const NamedDataMap* named_data_map = context.get_named_data_map();
-    Error err = compileModel(processed->data(), compute_graph, named_data_map);
+    Error err = compileModel(
+        processed->data(), processed->size(), compute_graph, named_data_map);
 
     // This backend does not need its processed data after compiling the
     // model.
diff --git a/backends/vulkan/runtime/VulkanDelegateHeader.cpp b/backends/vulkan/runtime/VulkanDelegateHeader.cpp
index 2a235144342..83bc263350b 100644
--- a/backends/vulkan/runtime/VulkanDelegateHeader.cpp
+++ b/backends/vulkan/runtime/VulkanDelegateHeader.cpp
@@ -84,7 +84,15 @@ bool VulkanDelegateHeader::is_valid() const {
   return true;
 }
 
-Result<VulkanDelegateHeader> VulkanDelegateHeader::parse(const void* data) {
+Result<VulkanDelegateHeader> VulkanDelegateHeader::parse(
+    const void* data,
+    size_t buffer_size) {
+  // Ensure the buffer is large enough to read all header fields.
+  // The last field (bytes_size) ends at offset 22 + 8 = 30 = kExpectedSize.
+  if (buffer_size < kExpectedSize) {
+    return Error::InvalidArgument;
+  }
+
   const uint8_t* header_data = (const uint8_t*)data;
 
   const uint8_t* magic_start = header_data + kMagic.offset;
@@ -104,6 +112,16 @@ Result<VulkanDelegateHeader> VulkanDelegateHeader::parse(const void* data) {
     return Error::InvalidArgument;
   }
 
+  // Validate that header offsets do not extend beyond the buffer.
+  if (header.flatbuffer_offset > buffer_size ||
+      header.flatbuffer_size > buffer_size - header.flatbuffer_offset) {
+    return Error::InvalidArgument;
+  }
+  if (header.bytes_offset > buffer_size ||
+      header.bytes_size > buffer_size - header.bytes_offset) {
+    return Error::InvalidArgument;
+  }
+
   return header;
 }
 
diff --git a/backends/vulkan/runtime/VulkanDelegateHeader.h b/backends/vulkan/runtime/VulkanDelegateHeader.h
index 722f01cbb75..312b08ab747 100644
--- a/backends/vulkan/runtime/VulkanDelegateHeader.h
+++ b/backends/vulkan/runtime/VulkanDelegateHeader.h
@@ -26,7 +26,8 @@ struct VulkanDelegateHeader {
   bool is_valid() const;
 
   static executorch::runtime::Result<VulkanDelegateHeader> parse(
-      const void* data);
+      const void* data,
+      size_t buffer_size);
 
   uint32_t header_size;
   uint32_t flatbuffer_offset;