A critical vulnerability, identified as CVE-2023-4813, has been discovered in the GNU C Library (glibc) that could potentially lead to application crashes. In some rare cases, the 'gaih_inet' function was found to be using memory that had already been freed, resulting in an application crash. It is important to note that this vulnerability can only be exploited if the 'getaddrinfo' function is called and the hosts database in /etc/nsswitch.conf is configured with either 'SUCCESS=continue' or 'SUCCESS=merge'.

Below is a sample code snippet that demonstrates possible usage of the 'getaddrinfo' function

#include <sys/socket.h>
#include <netdb.h>
#include <stdio.h>

int main(int argc, char *argv[])
    struct addrinfo hints, *result;
    int errno;

    memset(&hints, , sizeof(struct addrinfo));
    hints.ai_family = AF_UNSPEC; // Accept any address family
    hints.ai_socktype = SOCK_STREAM; // TCP stream

    if ((errno = getaddrinfo(argv[1], NULL, &hints, &result)) != )
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(errno));
        return 1;

    // Process the result and release the memory
    // ...


    return ;

As shown in the code, the 'getaddrinfo' function can be used to obtain address information for a given hostname. Critical flaws like CVE-2023-4813 can occur when the 'gaih_inet' function accesses memory that is no longer available, leading to an application crash.

Exploit Details

To exploit CVE-2023-4813, an attacker needs to take advantage of the 'gaih_inet' function use of freed memory in specific situations. The only scenario where this is exploitable is when the 'getaddrinfo' function is called, and the hosts database in /etc/nsswitch.conf is configured with 'SUCCESS=continue' or 'SUCCESS=merge'. In such cases, the attacker can potentially trigger an application crash.

To help understand the severity of this vulnerability, here's a possible crash scenario resulting from the exploitation of CVE-2023-4813:

An attacker crafts a scenario involving the 'getaddrinfo' function call.

2. The attacker ensures that the hosts database entry in /etc/nsswitch.conf file is set with either 'SUCCESS=continue' or 'SUCCESS=merge'.
3. When the 'gaih_inet' function is called during the 'getaddrinfo' function execution, the improper use of freed memory could lead to system instability or an application crash.

Original References

The flaw was originally reported in the glibc Bugzilla and further details can be found in the CVE database entry.


To protect systems from exploitation of this vulnerability, it is advised that users and administrators do the following:

Regularly check for and apply any available security patches or updates for glibc.

2. Review the configuration in /etc/nsswitch.conf file, particularly the hosts database entry, and ensure that 'SUCCESS=continue' or 'SUCCESS=merge' is not used unless absolutely necessary.

Stay informed on the latest security issues and vulnerabilities in software packages, and always ensure your systems are up-to-date with the latest security patches. By actively monitoring and addressing these threats, you can significantly reduce the risk of exposure to critical vulnerabilities such as CVE-2023-4813.


Published on: 09/12/2023 22:15:08 UTC
Last modified on: 11/10/2023 18:15:10 UTC