CVE-2023-29529

matrix-js-sdk is the Matrix Client-Server SDK for JavaScript and
TypeScript. An attacker present in a room where an MSC3401 group call is
taking place can eavesdrop on the video and audio of participants using
matrix-js-sdk, without their knowledge. To affected matrix-js-sdk users,
the attacker will not appear to be participating in the call. This attack
is possible because matrix-js-sdk’s group call implementation accepts
incoming direct calls from other users, even if they have not yet declared
intent to participate in the group call, as a means of resolving a race
condition in call setup. Affected versions do not restrict access to the
user’s outbound media in this case. Legacy 1:1 calls are unaffected. This
is fixed in matrix-js-sdk 24.1.0. As a workaround, users may hold group
calls in private rooms where only the exact users who are expected to
participate in the call are present.