A recently discovered vulnerability, CVE-2023-6378, in the logback receiver component, which is part of logback version 1.4.11 has opened the door for cybercriminals to potentially exploit systems and launch Denial-of-Service (DoS) attacks. In this post, we will discuss the nature of this vulnerability, share some examples of how an attacker could exploit the vulnerability, and provide recommendations for securing your system.

Vulnerability Details

The CVE-2023-6378 vulnerability stems from a serialization issue within the logback receiver component, which tracks and processes log messages in Java applications. Serialization is a process of converting an object's state into a byte stream so that it can be easily transferred or stored. Conversely, deserialization is the process of converting the byte stream back into an object. In the case of logback, an attacker can send malicious data (also known as poisoned data) to the logback receiver component, causing the application to crash or perform poorly.

Exploit Details

To successfully exploit this vulnerability, an attacker would need to send specially crafted data to the logback receiver component. This data could be sent via a variety of methods, such as through a network connection or by embedding the malicious data in a log message. When the receiver component attempts to process the poisoned data, it can cause the application to enter an infinite loop or otherwise disrupt normal operation, resulting in a Denial-of-Service attack.

Here's an example code snippet that demonstrates a potential exploit

import java.io.ByteArrayOutputStream;
import java.io.ObjectOutputStream;

public class Exploit {
    public static void main(String[] args) {
        // Create malicious data
        Object maliciousData = createMaliciousData();

        // Serialize the malicious data
        byte[] serializedData = serialize(maliciousData);

        // Send the serialized data to the logback receiver component

    private static Object createMaliciousData() {
        // Create an object with malicious data
        // ...

        return maliciousData;

    private static byte[] serialize(Object obj) {
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);
        return byteArrayOutputStream.toByteArray();

    private static void sendDataToLogbackReceiver(byte[] data) {
        // Establish a connection to the logback receiver component
        // ...

        // Send the serialized data
        // ...

Mitigation Steps

To protect your system from this vulnerability, it is crucial to update your logback installation to the latest version. The logback project has released version 1.4.12, which addresses this vulnerability and can be downloaded at the following link:

- Logback download: https://logback.qos.ch/download.html

In addition to upgrading logback, it is also recommended that you take the following precautionary measures:

- Regularly audit and review your logback configuration files to ensure that only trusted sources can send data to the logback receiver component.
- Increase monitoring and alerting for anomalous patterns in log messages to identify potential attacks.
- Investigate and apply other security best practices for log management and monitoring, such as limiting access to log files and encrypting log messages.


The CVE-2023-6378 vulnerability in the logback receiver component is a serious concern as it could let an attacker launch a Denial-of-Service attack on vulnerable systems. To mitigate and protect against this vulnerability, it is crucial to update your logback installation and take additional security measures. Stay ahead of possible exploits by staying informed and actively monitoring your systems.


Published on: 11/29/2023 12:15:07 UTC
Last modified on: 12/05/2023 21:00:10 UTC