Prototype pollution in matrix-js-sdk

matrix-js-sdk is a Matrix messaging protocol Client-Server SDK for JavaScript. In versions prior to 19.4.0 events sent with special strings in key places can temporarily disrupt or impede the matrix-js-sdk from functioning properly, potentially impacting the consumer's ability to process data safely. Note that the matrix-js-sdk can appear to be operating normally but be excluding or corrupting runtime data presented to the consumer. This issue has been fixed in matrix-js-sdk 19.4.0 and users are advised to upgrade. Users unable to upgrade may mitigate this issue by redacting applicable events, waiting for the sync processor to store data, and restarting the client. Alternatively, redacting the applicable events and clearing all storage will often fix most perceived issues. In some cases, no workarounds are possible.