CVE-2021-3640 : What You Need to Know

A flaw involving a use-after-free vulnerability in the Linux kernel HCI subsystem has been identified, impacting versions up to kernel v5.15.3. This vulnerability, assigned CVE-2021-3640, allows a privileged local user to crash the system or potentially elevate their privileges.

Understanding CVE-2021-3640

This section delves into the details of the CVE-2021-3640 vulnerability.

What is CVE-2021-3640?

The flaw involves a use-after-free vulnerability in function sco_sock_sendmsg() of the Linux kernel HCI subsystem. It occurs due to a race condition triggered by user calls like ioct UFFDIO_REGISTER.

The Impact of CVE-2021-3640

A local user with elevated privileges could exploit this vulnerability to crash the system or escalate their privileges, posing a significant security risk to affected systems.

Technical Details of CVE-2021-3640

Let's explore the technical aspects of CVE-2021-3640 in more detail.

Vulnerability Description

The vulnerability arises from a use-after-free issue in the Linux kernel HCI subsystem, specifically in the function sco_sock_sendmsg(). The flaw allows a privileged local user to interact with memory pages unpredictably, leading to system crashes or privilege escalation.

Affected Systems and Versions

CVE-2021-3640 impacts kernel versions up to v5.15.3. It is essential for users of these versions to be aware of the vulnerability and take necessary actions for mitigation.

Exploitation Mechanism

The vulnerability is exploited by triggering a race condition between the call sco_conn_del() and sco_sock_sendmsg(), allowing an attacker to manipulate faulting memory pages and execute arbitrary code.

Mitigation and Prevention

Discover the strategies to mitigate the risks posed by CVE-2021-3640.

Immediate Steps to Take

Users are advised to apply relevant patches and updates provided by the Linux kernel maintainers to address this vulnerability promptly.

Long-Term Security Practices

Incorporating proper privilege management and access controls can reduce the likelihood of exploitation of such vulnerabilities in the future.

Patching and Updates

Regularly monitor for security advisories and promptly apply patches released by the kernel maintainers to protect systems from known vulnerabilities.