added threat model section

XIPs/xip-48-content-type-local-db-integration.md

@@ -317,6 +317,10 @@ No new security considerations are introduced with this XIP. The security consid
 
 \* In the case of content types managed by the [XMTP GitHub organization](https://github.com/xmtp) the authority would be contributors/admins of the relevant GitHub repos.
 
+### Threat model
+
+As usual, users and developers should aspire to be using the latest XMTP SDK versions whenever possible, but you can never be sure whether inboxes you are chatting with on XMTP are using older or modified versions of the SDK. This means that users could configure their messages to specify that they are sending a certain content type, but the format, contents, or intentions of the actual data in the message could be something different. Fortunately, we haven't identified any security issues that would arise from this possibility, but it is something developers utilizing "complex decoding or presentation logic" as mentioned in the quote above, should be aware of. If any more specific threats or example of misuse arise, this section will be updated.
+
 ## Copyright
 
 Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).