CVE-2023-6546 Explained : Impact and Mitigation

This CVE record was published on December 21, 2023, by Red Hat. The vulnerability is related to a race condition in the GSM 0710 tty multiplexor in the Linux kernel, which could lead to privilege escalation for local unprivileged users.

Understanding CVE-2023-6546

This section provides a detailed understanding of the CVE-2023-6546 vulnerability.

What is CVE-2023-6546?

CVE-2023-6546 is a vulnerability in the GSM 0710 tty multiplexor in the Linux kernel. The issue arises when two threads execute the GSMIOC_SETCONF ioctl on the same tty file descriptor with the gsm line discipline enabled. This can lead to a use-after-free problem on a struct gsm_dlci while restarting the gsm mux, enabling a local unprivileged user to escalate their privileges on the system.

The Impact of CVE-2023-6546

The impact of CVE-2023-6546 is rated as "High" based on the CVSS v3.1 severity rating. The confidentiality, integrity, and availability of the affected system are at risk due to this vulnerability.

Technical Details of CVE-2023-6546

This section outlines the technical details of CVE-2023-6546.

Vulnerability Description

The vulnerability is a race condition in the GSM 0710 tty multiplexor in the Linux kernel, leading to a use-after-free issue on a specific data structure. This allows local unprivileged users to escalate their privileges.

Affected Systems and Versions

The vulnerability affects multiple versions of Red Hat Enterprise Linux, including versions 7, 8, and 9, as well as Fedora. Specific versions of the kernel package are listed as affected.

Exploitation Mechanism

The exploitation of CVE-2023-6546 involves triggering the race condition in the GSM 0710 tty multiplexor to exploit the use-after-free issue and gain escalated privileges.

Mitigation and Prevention

To mitigate the CVE-2023-6546 vulnerability, certain steps can be taken to enhance system security.

Immediate Steps to Take

A workaround for this flaw involves preventing the affected

n_gsm

kernel module from being loaded. Instructions on blacklisting a kernel module can be found on the Red Hat support page.

Long-Term Security Practices

Implementing strong user privilege management, regular system updates, and monitoring for suspicious activity can help prevent privilege escalation attacks.

Patching and Updates

Ensure that the affected systems are updated with the latest patches provided by Red Hat to address the CVE-2023-6546 vulnerability and enhance system security.