The client in Mumble 1.2.x before 1.2.6 allows remote attackers to force the loading of an external file and cause a denial of service (hang and resource consumption) via a crafted string that is treated as rich-text by a Qt widget, as demonstrated by the (1) user or (2) channel name in a Qt dialog, (3) subject common name or (4) email address to the Certificate Wizard, or (5) server name in a tooltip.

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.

The needSamples method in AudioOutputSpeech.cpp in the client in Mumble 1.2.4 and the 1.2.3 pre-release snapshots, Mumble for iOS 1.1 through 1.2.2, and MumbleKit before commit fd190328a9b24d37382b269a5674b0c0c7a7e36d does not check the return value of the opus_decode_float function, which allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted Opus voice packet, which triggers an error in opus_decode_float, a conversion of a negative integer to an unsigned integer, and a heap-based buffer over-read and over-write.

The opus_packet_get_samples_per_frame function in client in Mumble 1.2.4 and the 1.2.3 pre-release snapshots allows remote attackers to cause a denial of service (crash) via a crafted length prefix value, which triggers a NULL pointer dereference or a heap-based buffer over-read (aka "out-of-bounds array access").