diff --git a/Libraries/LibWeb/IndexedDB/Internal/Algorithms.cpp b/Libraries/LibWeb/IndexedDB/Internal/Algorithms.cpp
index efe4aa2dbd7..53859afff5f 100644
--- a/Libraries/LibWeb/IndexedDB/Internal/Algorithms.cpp
+++ b/Libraries/LibWeb/IndexedDB/Internal/Algorithms.cpp
@@ -22,6 +22,7 @@
 #include <LibWeb/IndexedDB/Internal/Database.h>
 #include <LibWeb/StorageAPI/StorageKey.h>
 #include <LibWeb/WebIDL/AbstractOperations.h>
+#include <LibWeb/WebIDL/Buffers.h>
 
 namespace Web::IndexedDB {
 
@@ -213,10 +214,14 @@ ErrorOr<GC::Ref<Key>> convert_a_value_to_a_key(JS::Realm& realm, JS::Value input
     // - If input is a buffer source type
     if (input.is_object() && (is<JS::TypedArrayBase>(input.as_object()) || is<JS::ArrayBuffer>(input.as_object()) || is<JS::DataView>(input.as_object()))) {
 
-        // 1. Let bytes be the result of getting a copy of the bytes held by the buffer source input. Rethrow any exceptions.
+        // 1. If input is [detached] then return invalid.
+        if (WebIDL::is_buffer_source_detached(input))
+            return Error::from_string_literal("Detached buffer is not supported as key");
+
+        // 2. Let bytes be the result of getting a copy of the bytes held by the buffer source input.
         auto data_buffer = TRY(WebIDL::get_buffer_source_copy(input.as_object()));
 
-        // 2. Return a new key with type binary and value bytes.
+        // 3. Return a new key with type binary and value bytes.
         return Key::create_binary(realm, data_buffer);
     }
 
diff --git a/Libraries/LibWeb/WebIDL/Buffers.cpp b/Libraries/LibWeb/WebIDL/Buffers.cpp
index e53aad280a1..6f056173192 100644
--- a/Libraries/LibWeb/WebIDL/Buffers.cpp
+++ b/Libraries/LibWeb/WebIDL/Buffers.cpp
@@ -127,4 +127,30 @@ void ArrayBufferView::write(ReadonlyBytes bytes, u32 starting_offset)
 
 BufferSource::~BufferSource() = default;
 
+// https://webidl.spec.whatwg.org/#buffersource-detached
+bool is_buffer_source_detached(JS::Value const& buffer_source)
+{
+    // A buffer source type instance bufferSource is detached if the following steps return true:
+
+    // 1. Let jsArrayBuffer be the result of converting bufferSource to a JavaScript value.
+    // 2. If jsArrayBuffer has a [[ViewedArrayBuffer]] internal slot, then set jsArrayBuffer to jsArrayBuffer.[[ViewedArrayBuffer]].
+    if (!buffer_source.is_object())
+        return false;
+
+    JS::ArrayBuffer const* js_array_buffer = nullptr;
+    auto const& array_buffer_object = buffer_source.as_object();
+    if (auto const* array_buffer = as_if<JS::ArrayBuffer>(array_buffer_object)) {
+        js_array_buffer = array_buffer;
+    } else if (auto const* typed_array_base = as_if<JS::TypedArrayBase>(array_buffer_object)) {
+        js_array_buffer = typed_array_base->viewed_array_buffer();
+    } else if (auto const* data_view = as_if<JS::DataView>(array_buffer_object)) {
+        js_array_buffer = data_view->viewed_array_buffer();
+    } else {
+        return false;
+    }
+
+    // 3. Return IsDetachedBuffer(jsArrayBuffer).
+    return js_array_buffer->is_detached();
+}
+
 }
diff --git a/Libraries/LibWeb/WebIDL/Buffers.h b/Libraries/LibWeb/WebIDL/Buffers.h
index ce9aebc72ee..46da8d20398 100644
--- a/Libraries/LibWeb/WebIDL/Buffers.h
+++ b/Libraries/LibWeb/WebIDL/Buffers.h
@@ -14,6 +14,8 @@
 
 namespace Web::WebIDL {
 
+bool is_buffer_source_detached(JS::Value const&);
+
 using BufferableObject = Variant<
     GC::Ref<JS::TypedArrayBase>,
     GC::Ref<JS::DataView>,