A critical heap-based buffer overflow vulnerability has been discovered in libjpeg-turbo, an open-source JPEG image codec. The vulnerability is assigned the identifier CVE-2023-2804 and is present in the h2v2_merged_upsample_internal() function within the jdmrgext.c file. This article aims to provide an in-depth understanding of the exploit, its potential impact, and possible mitigation strategies. We will also delve into the source code to provide code snippets and reference the original references to provide a comprehensive overview of the issue.

Background

libjpeg-turbo is a popular open-source JPEG image codec used by numerous applications for reading, writing, and processing JPEG images. Given its widespread usage, a vulnerability in the library can have widespread ramifications, potentially compromising several applications that rely on it for processing JPEG images.

Exploit Details

The CVE-2023-2804 vulnerability is a heap-based buffer overflow that can be exploited with 12-bit data precision. The issue stems from the fact that the range of the sample data type exceeds the valid sample range. This means an attacker could craft a 12-bit lossless JPEG image containing out-of-range 12-bit samples that, when processed by libjpeg-turbo using merged upsampling, could trigger a segmentation fault or buffer overflows.

Here's a code snippet from the jdmrgext.c file, showcasing the h2v2_merged_upsample_internal() function:

static void
h2v2_merged_upsample_internal (j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
                               JDIMENSION in_row_group_ctr,
                               JSAMPARRAY *output_ptr)
{
  ...
}

When an application attempts to decompress a malicious JPEG image crafted to exploit this vulnerability, it would lead to a crash, potentially compromising the application's stability and security.

Original References

1. The complete source code for libjpeg-turbo can be found on their official GitHub repository: https://github.com/libjpeg-turbo/libjpeg-turbo
2. The CVE entry for CVE-2023-2804 can be found here: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-2804

Mitigation

As of the time of writing, there has been no official patch released to address this vulnerability. However, application developers and users can take the following steps to minimize or mitigate the impact of the exploit:

1. Monitor the libjpeg-turbo GitHub repository and CVE-2023-2804 page for updates and patches addressing the vulnerability.
2. Proceed with caution when processing or displaying JPEG images from untrusted sources in applications relying on libjpeg-turbo.
3. Consider alternative libraries or temporary mitigations (e.g., input sanitization, upgrading to a non-vulnerable version) until a patch is released.

Conclusion

The heap-based buffer overflow vulnerability in libjpeg-turbo's h2v2_merged_upsample_internal() function poses a significant threat to applications relying on the library for processing JPEG images. As the vulnerability only affects processing of 12-bit lossless JPEG images with out-of-range samples, developers and users of libjpeg-turbo should be cautious when handling such images. As no official patch has been released yet, users should keep an eye on the aforementioned references for updates and take necessary precautions to minimize the risk posed by this vulnerability.

Timeline

Published on: 05/25/2023 22:15:00 UTC
Last modified on: 06/06/2023 13:40:00 UTC