diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
index 415bb47a19..768fb5c28c 100644
--- a/docs/interop/vhost-user.rst
+++ b/docs/interop/vhost-user.rst
@@ -275,6 +275,16 @@ Inflight description
 
 :queue size: a 16-bit size of virtqueues
 
+VhostUserShared
+^^^^^^^^^^^^^^^
+
++------+
+| UUID |
++------+
+
+:UUID: 16 bytes UUID, whose first three components (a 32-bit value, then
+  two 16-bit values) are stored in big endian.
+
 C structure
 -----------
 
@@ -885,6 +895,7 @@ Protocol features
   #define VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS  15
   #define VHOST_USER_PROTOCOL_F_STATUS               16
   #define VHOST_USER_PROTOCOL_F_XEN_MMAP             17
+  #define VHOST_USER_PROTOCOL_F_SHARED_OBJECT        18
 
 Front-end message types
 -----------------------
diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h
index 6b06ecb1bd..20b69d8e85 100644
--- a/include/hw/virtio/vhost-user.h
+++ b/include/hw/virtio/vhost-user.h
@@ -29,7 +29,8 @@ enum VhostUserProtocolFeature {
     VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS = 14,
     VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS = 15,
     VHOST_USER_PROTOCOL_F_STATUS = 16,
-    VHOST_USER_PROTOCOL_F_SHARED_OBJECT = 17,
+    /* Feature 17 reserved for VHOST_USER_PROTOCOL_F_XEN_MMAP. */
+    VHOST_USER_PROTOCOL_F_SHARED_OBJECT = 18,
     VHOST_USER_PROTOCOL_F_MAX
 };
 
diff --git a/subprojects/libvhost-user/libvhost-user.h b/subprojects/libvhost-user/libvhost-user.h
index b36a42a7ca..c2352904f0 100644
--- a/subprojects/libvhost-user/libvhost-user.h
+++ b/subprojects/libvhost-user/libvhost-user.h
@@ -65,7 +65,8 @@ enum VhostUserProtocolFeature {
     VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS = 14,
     VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS = 15,
     /* Feature 16 is reserved for VHOST_USER_PROTOCOL_F_STATUS. */
-    VHOST_USER_PROTOCOL_F_SHARED_OBJECT = 17,
+    /* Feature 17 reserved for VHOST_USER_PROTOCOL_F_XEN_MMAP. */
+    VHOST_USER_PROTOCOL_F_SHARED_OBJECT = 18,
     VHOST_USER_PROTOCOL_F_MAX
 };