CVE-2020-14346: X.Org Server XIChangeHierarchy Integer Underflow Privilege Escalation Vulnerability

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.

— Red Hat

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.

— ZDI

X.Org server could allow a local authenticated attacker to gain elevated privileges on the system, caused by an integer underflow in XIChangeHierarchy. By sending a specially-crafted request, an authenticated attacker could exploit this vulnerability to gain elevated privileges.

— IBM