CVE-2021-4203 : Security Advisory and Response

A use-after-free read flaw in the Linux kernel's sock_getsockopt() function in net/core/sock.c allows an attacker with user privileges to crash the system or leak internal kernel information.

Understanding CVE-2021-4203

This CVE highlights a vulnerability in the Linux kernel that could be exploited by an attacker to cause system crashes or access sensitive kernel data.

What is CVE-2021-4203?

CVE-2021-4203 is a use-after-free read flaw in the sock_getsockopt() function in the Linux kernel, which could be abused by an attacker with normal user privileges to crash the system or disclose internal kernel details.

The Impact of CVE-2021-4203

The impact of this vulnerability is severe as it allows an attacker to either crash the system or potentially retrieve sensitive information from the kernel, leading to potential security breaches.

Technical Details of CVE-2021-4203

This section delves into the specifics of the vulnerability.

Vulnerability Description

The flaw occurs due to a race condition with SO_PEERCRED and SO_PEERGROUPS in sock_getsockopt() when combined with listen() or connect().

Affected Systems and Versions

The affected product is the kernel, specifically version kernel 5.15 rc4.

Exploitation Mechanism

An attacker with user privileges could exploit this vulnerability, triggering a use-after-free read flaw in the Linux kernel's sock_getsockopt() function.

Mitigation and Prevention

Here are the necessary steps to mitigate and prevent exploits leveraging CVE-2021-4203.

Immediate Steps to Take

Users are advised to apply patches provided by the Linux kernel maintainers promptly.

Long-Term Security Practices

Following security best practices, such as regular system updates and access control, can reduce the risk of exploitation.

Patching and Updates

Stay informed about security updates released by the Linux kernel team and apply them diligently to safeguard your systems.