CVE-2021-20268 : Security Advisory and Response

An out-of-bounds access flaw in the Linux kernel's eBPF code verifier allows a local user to crash the system or escalate privileges, posing a threat to confidentiality, integrity, and system availability.

Understanding CVE-2021-20268

This vulnerability affects the Linux kernel, specifically version 5.10.10, and can be exploited by a user running an eBPF script.

What is CVE-2021-20268?

CVE-2021-20268 is a flaw in the eBPF code verifier implementation of the Linux kernel, impacting the way certain functions are called by user scripts, potentially leading to system crashes or privilege escalation.

The Impact of CVE-2021-20268

The highest risk posed by this vulnerability is to the confidentiality, integrity, and availability of affected systems. A local user could exploit this flaw to compromise system security.

Technical Details of CVE-2021-20268

This section provides detailed information about the vulnerability, including its description, affected systems and versions, and the exploitation mechanism.

Vulnerability Description

The vulnerability arises from an out-of-bounds access flaw in the eBPF code verifier, triggered by specific function calls in user scripts, allowing for system crashes and potential privilege escalation.

Affected Systems and Versions

The vulnerability impacts systems running the Linux kernel version 5.10.10, where users executing eBPF scripts are at risk of exploiting this flaw.

Exploitation Mechanism

By calling specific functions like dev_map_init_map or sock_map_alloc in the eBPF script, a local user can abuse this vulnerability to disrupt system operations or gain elevated privileges.

Mitigation and Prevention

To safeguard systems from CVE-2021-20268, immediate steps should be taken to mitigate the risk and prevent potential exploitation.

Immediate Steps to Take

Users are advised to update their Linux kernel to a patched version, follow security advisories, and monitor for any unusual system behavior that could indicate an attempted exploit.

Long-Term Security Practices

Implementing security best practices such as least privilege access, regular security updates, and code review processes can enhance system resilience against similar vulnerabilities.

Patching and Updates

Regularly check for security patches and updates provided by the Linux kernel maintainers to address CVE-2021-20268 and other known security issues.