CVE-2019-20382

QEMU versión 4.1.0, presenta una pérdida de memoria en la función zrle_compress_data en el archivo ui/vnc-enc-zrle.c durante una operación de desconexión de VNC porque libz es usada inapropiadamente, resultando en una situación donde la memoria asignada en deflateInit2 no es liberada en deflateEnd.

A memory leakage flaw was found in the way the VNC display driver of QEMU handled the connection disconnect when ZRLE and Tight encoding are enabled. Two VncState objects are created, and one allocates memory for the Zlib's data object. This allocated memory is not freed upon disconnection, resulting in a memory leak. An attacker able to connect to the VNC server could use this flaw to leak host memory, leading to a potential denial of service.

It was discovered that QEMU incorrectly handled bochs-display devices. A local attacker in a guest could use this to cause a denial of service or possibly execute arbitrary code in the host. This issue only affected Ubuntu 19.10. It was discovered that QEMU incorrectly handled memory during certain VNC operations. A remote attacker could possibly use this issue to cause QEMU to consume resources, resulting in a denial of service. This issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 19.10. Various other issues were also addressed.