CVE-2021-22600 : What You Need to Know

A double free bug in packet_set_ring() in net/packet/af_packet.c can be exploited by a local user through crafted syscalls to escalate privileges or deny service. It is recommended to upgrade the kernel past the affected versions or rebuild past ec6af094ea28f0f2dda1a6a33b14cd57e36a9755.

Understanding CVE-2021-22600

This CVE identifies a double free vulnerability in the Linux Kernel's

net/packet/af_packet.c

file. Exploiting this vulnerability can lead to privilege escalation for a local user.

What is CVE-2021-22600?

The CVE-2021-22600 vulnerability involves a double free bug in

packet_set_ring()

within

net/packet/af_packet.c

. By leveraging this flaw, a local user can execute specially crafted syscalls to either elevate their privileges or disrupt services.

The Impact of CVE-2021-22600

The impact of this vulnerability is significant as it allows an attacker to potentially escalate their privileges on the system or cause denial of service by exploiting the double free bug.

Technical Details of CVE-2021-22600

This section provides a deeper insight into the technical aspects of the CVE.

Vulnerability Description

The root of the issue lies in the

packet_set_ring()

function within

net/packet/af_packet.c

where a double free bug exists. This bug can be abused by a local user to manipulate syscalls for malicious privilege escalation or service disruption.

Affected Systems and Versions

The vulnerability impacts the Linux Kernel's

Kernel

product with versions less than

5.4.168

,

5.10.88

,

5.15.11

, and

5.16-rc6

.

Exploitation Mechanism

Exploiting this vulnerability requires crafting specific syscalls to trigger the double free bug in

packet_set_ring()

, subsequently enabling privilege escalation or denial of service attacks.

Mitigation and Prevention

To safeguard systems from CVE-2021-22600, immediate steps and long-term security practices need to be implemented.

Immediate Steps to Take

Upgrade the Linux Kernel to a version beyond the impacted ones.
Monitor and restrict local user access to critical system components.

Long-Term Security Practices

Implement regular security patches and updates to the kernel.
Conduct security training to enhance awareness of privilege escalation risks.

Patching and Updates

Refer to the following links for patches and detailed security advisories:

linux.git Patch Commit
Debian LTS Security Update DLA 2941-1
Debian Security Advisory DSA-5096
NetApp Security Advisory