CVE-2020-14346

Se encontró un fallo en xorg-x11-server versiones anteriores a 1.20.9. Un subdesbordamiento de enteros en la decodificación del protocolo de extensión de entrada X en el servidor X puede conllevar a un acceso arbitrario al contenido de la memoria. La mayor amenaza de esta vulnerabilidad es la confidencialidad e integridad de los datos, así como la disponibilidad del sistema

A flaw was found in xorg-x11-server. A integer underflow in the X input extension protocol decoding in the X server may lead to arbitrary access of memory contents. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

This vulnerability allows local attackers to escalate privileges on affected installations of X.Org Server. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.
The specific flaw exists within the handling of XIChangeHierarchy requests. The issue results from the lack of proper validation of user-supplied data, which can result in an integer underflow before writing to memory. An attacker can leverage this vulnerability to escalate privileges and execute code in the context of root.

USN-4488-1 fixed several vulnerabilities in X.Org. This update provides the corresponding update and also the update from USN-4490-1 for Ubuntu 14.04 ESM. Jan-Niklas Sohn discovered that the X.Org X Server incorrectly handled the input extension protocol. A local attacker could possibly use this issue to escalate privileges. Jan-Niklas Sohn discovered that the X.Org X Server incorrectly initialized memory. A local attacker could possibly use this issue to obtain sensitive information. Jan-Niklas Sohn discovered that the X.Org X Server incorrectly handled the XkbSelectEvents function. A local attacker could possibly use this issue to escalate privileges. Jan-Niklas Sohn discovered that the X.Org X Server incorrectly handled the XRecordRegisterClients function. A local attacker could possibly use this issue to escalate privileges.