diff --git a/Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Boxes.cpp b/Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Boxes.cpp
index 3658dd9b085..af8c916a59d 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Boxes.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Boxes.cpp
@@ -120,4 +120,28 @@ void SuperBox::dump(String const& prepend) const
         child_box->dump(indented_prepend);
 }
 
+ErrorOr<void> UserExtensionBox::read_from_stream(BoxStream& stream)
+{
+    // unsigned int(8)[16] uuid;
+    TRY(stream.read_until_filled(uuid));
+    // unsigned int(8) data[];
+    data = TRY(ByteBuffer::create_uninitialized(stream.remaining()));
+    TRY(stream.read_until_filled(data));
+    return {};
+}
+
+void UserExtensionBox::dump(String const& prepend) const
+{
+    Box::dump(prepend);
+
+    auto indented_prepend = add_indent(prepend);
+
+    out("{}- uuid = ", prepend);
+    for (auto byte : uuid)
+        out("{:02x}"sv, byte);
+    outln();
+
+    outln("{}- data = [ {} bytes ]", prepend, data.size());
+}
+
 }
diff --git a/Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Boxes.h b/Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Boxes.h
index ea3935764e9..d909e1fddb1 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Boxes.h
+++ b/Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Boxes.h
@@ -106,4 +106,11 @@ private:
     BoxList m_child_boxes;
 };
 
+struct UserExtensionBox final : public Box {
+    BOX_SUBTYPE(UserExtensionBox);
+
+    Array<u8, 16> uuid;
+    ByteBuffer data;
+};
+
 }
diff --git a/Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Reader.cpp b/Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Reader.cpp
index e5466d45d6e..aa7fabba964 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Reader.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Reader.cpp
@@ -35,6 +35,8 @@ ErrorOr<BoxList> Reader::read_entire_file()
             return TRY(JPEG2000SignatureBox::create_from_stream(stream));
         case BoxType::JPEG2000UUIDInfoBox:
             return TRY(JPEG2000UUIDInfoBox::create_from_stream(stream));
+        case BoxType::UserExtensionBox:
+            return TRY(UserExtensionBox::create_from_stream(stream));
         default:
             return OptionalNone {};
         }