CVE-2023-5380 : What You Need to Know

A use-after-free vulnerability has been discovered in the xorg-x11-server, impacting certain configurations and leading to potential X server crashes. This CVE was reported to Red Hat and made public on October 25, 2023.

Understanding CVE-2023-5380

This section will provide an overview of CVE-2023-5380, including its description, impact, affected systems, and technical details.

What is CVE-2023-5380?

CVE-2023-5380 is a use-after-free flaw found in the xorg-x11-server. Specifically, an X server crash may occur in a very specific and legacy configuration involving a multi-screen setup with multiple protocol screens (Zaphod mode). This crash scenario is triggered when a pointer is warped from within a window on one screen to the root window of the other screen, followed by the destruction of the original window and another window.

The Impact of CVE-2023-5380

The vulnerability poses a moderate risk, with a CVSS base score of 4.7 (medium severity). It has a high availability impact in local attack scenarios, but does not directly impact confidentiality or integrity. However, successful exploitation could lead to X server crashes in affected configurations.

Technical Details of CVE-2023-5380

Here, we delve into the vulnerability description, affected systems and versions, as well as the exploitation mechanism.

Vulnerability Description

The use-after-free vulnerability in xorg-x11-server may result in X server crashes under specific conditions involving multi-screen setups and certain window destruction sequences.

Affected Systems and Versions

Xorg-server: Version 21.1.9 is unaffected.
Red Hat Enterprise Linux 7: Versions 0:1.8.0-26.el7_9 of 'tigervnc' are affected.
Red Hat Enterprise Linux 6, 8, 9 and Fedora: Various packages and versions are affected, including 'xorg-x11-server' and 'tigervnc'.

Exploitation Mechanism

The vulnerability can be exploited in scenarios where a pointer is moved between windows in a multi-screen setup, leading to the destruction of certain windows and subsequent crashes.

Mitigation and Prevention

To address CVE-2023-5380, it is essential to take immediate steps, implement long-term security practices, and apply relevant patches and updates.

Immediate Steps to Take

Monitor Vendor Advisories: Stay updated on security advisories from Red Hat, Fedora, and other relevant vendors.
Follow Best Practices: Limit exposure by monitoring and controlling the movement of pointers between windows.

Long-Term Security Practices

Regular Security Audits: Conduct routine security audits to identify and address vulnerabilities.
Security Training: Educate users on secure practices to prevent exploitation.

Patching and Updates

Apply Vendor Patches: Install patches provided by Red Hat, Fedora, and other affected vendors to mitigate the vulnerability.
Update Software: Keep all software and packages up-to-date to prevent exploitation of known vulnerabilities.

By following these mitigation strategies, organizations can enhance their security posture and reduce the risk associated with CVE-2023-5380.