CVE-2020-14362: 
NixOS vulnerability analysis and mitigation

A flaw was discovered in X.Org Server before version 1.20.9, identified as CVE-2020-14362. The vulnerability involves an integer underflow leading to heap-buffer overflow in the XRecordRegisterClients function, which could potentially lead to privilege escalation. The issue was discovered by Jan-Niklas Sohn working with Trend Micro Zero Day Initiative and was disclosed on August 25, 2020 (X.Org Announce).

The vulnerability exists within the handling of XRecordRegisterClients requests in the X record extension. The specific flaw stems from the lack of proper validation of user-supplied data, which can result in an integer underflow before writing to memory. The vulnerability has been assigned a CVSS v3.1 base score of 7.8 (High), with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, indicating local access requirements with low attack complexity (ZDI Advisory).

The vulnerability poses a significant security risk as it could allow local attackers to escalate privileges and execute code in the context of root. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability (MITRE CVE).

The vulnerability requires local access to exploit, with an attacker needing the ability to execute low-privileged code on the target system. The attack complexity is considered low, requiring minimal conditions for exploitation (ZDI Advisory).

The vulnerability has been fixed in X.Org Server version 1.20.9. The fix was committed to the xorg server git repository with commit 24acad216aa0fc2ac451c67b2b86db057a032050. Users are advised to upgrade to this version or later to mitigate the vulnerability (X.Org Announce).

Red Hat has rated this issue as having moderate impact for Red Hat Enterprise Linux 8, noting that Xorg server does not run with root privileges in their implementation (Red Hat Bugzilla).