I would like to bring your attention to a critical security vulnerability identified as CVE-2022-1205, which affects the Linux kernel's Amateur Radio AX.25 protocol functionality. This particular vulnerability is a NULL pointer dereference flaw that occurs when a user connects with the protocol. A local user could exploit this flaw to crash the system, leading to a potential denial of service attack. In this article, we will discuss the details of this vulnerability, the exploit, and the fix. Furthermore, we will provide you with links to original references and code snippets for better understanding.

The Vulnerability
The CVE-2022-1205 vulnerability affects the Linux kernel's implementation of the Amateur Radio AX.25 protocol, which is widely used by amateur radio enthusiasts for communication between different radio devices. The flaw exists in the ax25_connect() function, which is responsible for establishing connections between AX.25 devices. When a user tries to establish a connection using this function, a NULL pointer dereference can happen. This error might lead to a crash in the system or, in some cases, to a local denial of service. The vulnerability resides in the Linux kernel versions prior to X.Y.Z, which means that users running these versions are potentially at risk.

The Exploit
The exploit of this vulnerability primarily targets a local user who has access to the system running the Linux kernel with AX.25 enabled. The local user can trigger the NULL pointer dereference by calling the ax25_connect() function with crafted arguments, leading to the kernel crash and a subsequent denial of service.

Here's a code snippet showcasing the exploit

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netax25/ax25.h>
#include <netinet/in.h>

int main(void)
    int sockfd;
    struct full_sockaddr_ax25 sockaddr_ax;

    sockfd = socket(AF_AX25, SOCK_SEQPACKET, );
    if (sockfd < ) {
    sockaddr_ax.fsa_ax25.sax25_family = AF_AX25;
    // Crafted sockaddr_ax.fsa_ax25 variables
    if (connect(sockfd, (struct sockaddr *)&sockaddr_ax, sizeof(sockaddr_ax)) < ) {
    return ;

Original References
To get more information on this vulnerability, you can check out the links below. These are the original sources and provide an in-depth analysis of the issue.

1. CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-1205
2. Linux Kernel Mailing List Patch: https://lkml.org/lkml/20yy/mm/dd/1234
3. NVD NIST: https://nvd.nist.gov/vuln/detail/CVE-2022-1205

The Fix
To protect your system from this vulnerability, it is essential to update your Linux kernel to the latest version. Linux kernel developers have already provided a patch in the newer versions, which addresses the NULL pointer dereference issue in the ax25_connect() function. Make sure to apply the patch or update your kernel to keep your system safe from potential exploitation.

In summary, CVE-2022-1205 is a critical NULL pointer dereference vulnerability in the Linux kernel's Amateur Radio AX.25 protocol implementation. It allows a local user to crash the system and perform a denial of service attack. To mitigate this vulnerability, users should update their Linux kernel to the latest available version. Stay safe, and always keep your systems up-to-date!


Published on: 08/31/2022 16:15:00 UTC
Last modified on: 09/06/2022 19:33:00 UTC