diff --git a/modules/window-thumbnail/core/graphics-memory-buffer.cpp b/modules/window-thumbnail/core/graphics-memory-buffer.cpp
index edaa00b931fef8643fe68c4bdfb7bbb44ff0a0a1..e6e1bdc9ab7411cdb9abdd045d078fbf2d437e33 100644
--- a/modules/window-thumbnail/core/graphics-memory-buffer.cpp
+++ b/modules/window-thumbnail/core/graphics-memory-buffer.cpp
@@ -101,7 +101,8 @@ bool GraphicsMemoryBuffer::createDmabufResources()
           EGL_DMA_BUF_PLANE3_MODIFIER_LO_EXT, EGL_DMA_BUF_PLANE3_MODIFIER_HI_EXT }
     };
 
-    for (uint32_t i = 0; i < m_bufferInfo.n_planes; i++) {
+    const uint32_t planeCount = qMin(m_bufferInfo.n_planes, 4u);
+    for (uint32_t i = 0; i < planeCount; i++) {
         ADD_ATTRIB(attr_names[i].fd, m_bufferInfo.planes[i].fd);
         ADD_ATTRIB(attr_names[i].offset, m_bufferInfo.planes[i].offset);
         ADD_ATTRIB(attr_names[i].pitch, m_bufferInfo.planes[i].stride);
diff --git a/platform/wayland/kywc-capture-manager.cpp b/platform/wayland/kywc-capture-manager.cpp
index 2d536ed91ec03bedede7766f7249088727c57c9b..f8b1bb9cc48981a52030eb3b8ddbf886a1936b8c 100644
--- a/platform/wayland/kywc-capture-manager.cpp
+++ b/platform/wayland/kywc-capture-manager.cpp
@@ -195,6 +195,11 @@ void KywcCaptureFrame::Private::bufferWithPlaneCallback(void *data, kywc_capture
         return;
     }
 
+    if (index >= 4) {
+        close(fd);
+        return;
+    }
+
     p->currentBuffer.planes[index].fd = fd;
     p->currentBuffer.planes[index].offset = offset;
     p->currentBuffer.planes[index].stride = stride;