Matrix: apparently reply sources reveal prior messages to new users in E2EE rooms

[Mikaela]

1. Send a message in an encrypted room
2. Someone1 joins a room
3. Someone2 replies to the first message
4. Someone1 can view source of Someone2's message and thus sees what the first message had.

TODO: Does an issue exist about this? This belongs to https://mikaela.info/blog/english/2021/08/03/matrix-perfect-privacy-not.html

[Mikaela]

Confirmed by myself. It's in body and formatted_body.

[Mikaela]

This may be another case of https://github.com/matrix-org/matrix-doc/issues/2678#issuecomment-934215284 where I am already linking to?

[Mikaela]

no, that problem is covered in https://github.com/matrix-org/matrix-doc/issues/1654, and also in the MSC matrix-org/matrix-spec-proposals#2781.

• https://github.com/matrix-org/matrix-doc/issues/2678#issuecomment-934275287