CVE-2022-39249

Matrix Javascript SDK is the Matrix Client-Server SDK for JavaScript. Prior
to version 19.7.0, an attacker cooperating with a malicious homeserver can
construct messages appearing to have come from another person. Such
messages will be marked with a grey shield on some platforms, but this may
be missing in others. This attack is possible due to the matrix-js-sdk
implementing a too permissive key forwarding strategy on the receiving end.
Starting with version 19.7.0, the default policy for accepting key forwards
has been made more strict in the matrix-js-sdk. matrix-js-sdk will now only
accept forwarded keys in response to previously issued requests and only
from own, verified devices. The SDK now sets a trusted flag on the
decrypted message upon decryption, based on whether the key used to decrypt
the message was received from a trusted source. Clients need to ensure that
messages decrypted with a key with trusted = false are decorated
appropriately, for example, by showing a warning for such messages. This
attack requires coordination between a malicious homeserver and an
attacker, and those who trust your homeservers do not need a workaround.