Snappy-java is a popular and efficient Java-based compressor/decompressor which provides fast compression and decompression capabilities. Recently, a vulnerability (CVE-2023-34453) has been identified in snappy-java versions prior to This vulnerability is caused by an integer overflow due to unchecked multiplications, which may eventually lead to a fatal error in the application. In this blog post, we will discuss the details of the vulnerability, along with a code snippet, original references and the exploit details.

Vulnerability Details

The issue lies in the shuffle(int[] input) function in the file. The function takes an array of integers as input and performs a bit shuffle on it. The operation involves multiplying the length of the input array by 4 and passing the result to the natively compiled shuffle function. Unfortunately, the input array length is not checked before the multiplication, causing a potential integer overflow that could result in a smaller value, zero, or even a negative number.

If a negative value is produced, a java.lang.NegativeArraySizeException exception will be raised, leading to a program crash. Furthermore, if the value is zero or too small, any code that references the shuffled array afterward will incorrectly assume a larger size for the array, potentially causing exceptions such as java.lang.ArrayIndexOutOfBoundsException.

Code Snippet

public static void shuffle(int[] data) {
    int len = data.length * 4; // Unchecked multiplication causing vulnerability
    shuffle(data, len);

The vulnerability also extends to other shuffle functions that handle the double, float, long, and short data types, as they use different multipliers, potentially leading to the same issue.

Patched Version

Version of snappy-java contains a patch for this vulnerability. Users are strongly encouraged to update their snappy-java library to the latest version to avoid any potential exploitation.

Original References

1. CVE-2023-34453 - Official CVE Description
2. Snappy-java Github Repository
3. Snappy-java Version Release Notes

Exploit Details

An attacker could exploit this vulnerability by crafting a malicious input array with a carefully chosen length that would trigger an integer overflow when interacting with the shuffle functions in the snappy-java library. This would result in either crashes (java.lang.NegativeArraySizeException thrown) or unexpected behaviors (java.lang.ArrayIndexOutOfBoundsException thrown) in the application using the library.


To mitigate the CVE-2023-34453 vulnerability in snappy-java, it is imperative to update to the latest version ( which includes the necessary patch. Also, it is always a good practice to validate the inputs of any external libraries and APIs to reduce any potential risks.


Published on: 06/15/2023 17:15:00 UTC
Last modified on: 06/27/2023 15:59:00 UTC