murmur in Mumble through 1.2.19 before 2018-08-31 mishandles multiple concurrent requests that are persisted in the database, which allows remote attackers to cause a denial of service (daemon hang or crash) via a message flood.
The QSvg module in Qt, as used in the Mumble client 1.2.x before 1.2.6, allows remote attackers to cause a denial of service (hang and resource consumption) via a local file reference in an (1) image tag or (2) XML stylesheet in an SVG file.
Mumble 1.2.3 and earlier uses world-readable permissions for .local/share/data/Mumble/.mumble.sqlite files in home directories, which might allow local users to obtain a cleartext password and configuration data by reading a file.