CVE-2023-2804: Libjpeg-turbo Buffer Overflow Vulnerability

CVE-2023-2804 Overview

A heap-based buffer overflow vulnerability was discovered in libjpeg-turbo within the h2v2_merged_upsample_internal() function located in the jdmrgext.c file. This vulnerability can only be exploited when processing JPEG images with 12-bit data precision, where the range of the sample data type exceeds the valid sample range. An attacker could craft a malicious 12-bit lossless JPEG image containing out-of-range 12-bit samples. When an application attempts to decompress such an image using merged upsampling, it would lead to a segmentation fault or buffer overflow, causing the application to crash.

Critical Impact

Applications using libjpeg-turbo to process untrusted 12-bit lossless JPEG images may crash due to heap-based buffer overflow, resulting in denial of service conditions.

Affected Products

• libjpeg-turbo version 2.1.90
• Applications and systems utilizing libjpeg-turbo for JPEG image processing
• Intel products affected as noted in Intel Security Advisory SA-01006

Discovery Timeline

• May 25, 2023 - CVE-2023-2804 published to NVD
• January 16, 2025 - Last updated in NVD database

Technical Details for CVE-2023-2804

Vulnerability Analysis

This vulnerability is classified as CWE-122 (Heap-based Buffer Overflow) and CWE-787 (Out-of-bounds Write). The flaw exists specifically in the merged upsampling code path used during JPEG decompression. When processing 12-bit lossless JPEG images, the library fails to properly validate that sample values fall within the expected range for 12-bit precision. Since 12-bit samples should only contain values from 0 to 4095, but the underlying data type can hold larger values, maliciously crafted images can contain out-of-range samples that trigger buffer overflows when the merged upsampling functions attempt to process them.

The vulnerability requires user interaction—a victim must open or process a maliciously crafted JPEG file. While the impact is limited to availability (causing application crashes), this could be significant in server environments that process user-uploaded images or in applications that handle untrusted image content.

Root Cause

The root cause lies in the lack of proper range-limiting for 12-bit sample values during lossless JPEG decompression. The h2v2_merged_upsample_internal() function in jdmrgext.c processes sample data without verifying that the values conform to the valid 12-bit range (0-4095). When out-of-range values are encountered, they cause the function to access memory outside the allocated buffer boundaries, resulting in heap corruption.

Attack Vector

An attacker exploits this vulnerability by crafting a specially constructed 12-bit lossless JPEG image file. The attack requires the following conditions:

1. The target application must use a vulnerable version of libjpeg-turbo
2. The application must process JPEG images with 12-bit data precision
3. The application must use merged upsampling during decompression
4. The victim must open or process the malicious image file

The attack is delivered over the network, typically through image uploads, email attachments, or web content, but requires user interaction to trigger the vulnerable code path.

  * Lossless JPEG Modifications:
  * Copyright (C) 1999, Ken Murchison.
  * libjpeg-turbo Modifications:
- * Copyright (C) 2022, D. R. Commander.
+ * Copyright (C) 2022-2023, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README.ijg
  * file.
  *

Source: GitHub Commit for libjpeg-turbo

The patch introduces range-limiting for 12-bit samples during lossless decompression to ensure values stay within valid bounds.

Detection Methods for CVE-2023-2804

Indicators of Compromise

• Application crashes or segmentation faults when processing JPEG images
• Unexpected termination of image processing services or applications
• Core dumps or crash logs indicating heap corruption in libjpeg-turbo functions
• Error messages referencing h2v2_merged_upsample_internal() or jdmrgext.c

Detection Strategies

• Monitor application logs for crashes related to JPEG image processing
• Implement file integrity monitoring for libjpeg-turbo library files to detect version changes
• Use memory sanitizers (AddressSanitizer, Valgrind) in development and testing environments to detect heap overflows
• Deploy application-level monitoring to track unusual image processing failures

Monitoring Recommendations

• Audit systems to identify libjpeg-turbo version 2.1.90 and earlier vulnerable versions
• Monitor for unusual patterns in image upload or processing workflows
• Track crash reports and memory corruption events in applications that handle JPEG images
• Review security advisories from Red Hat and other vendors for updated guidance

How to Mitigate CVE-2023-2804

Immediate Actions Required

• Update libjpeg-turbo to the latest patched version that includes the security fix
• If updates cannot be immediately applied, consider disabling 12-bit JPEG processing if your application permits
• Review and restrict sources of JPEG images processed by affected systems
• Implement input validation to reject suspicious or malformed JPEG files

Patch Information

The vulnerability has been addressed in the libjpeg-turbo project. The fix introduces range-limiting for 12-bit samples during lossless JPEG decompression. Organizations should:

1. Apply the patch from GitHub Commit 9f756bc67a84d4566bf74a0c2432aa55da404021
2. Update via package managers where available (check vendor-specific repositories)
3. Consult the Red Hat Bug Report #2208447 for distribution-specific updates
4. Review GitHub Issue #675 for additional context and discussion

Workarounds

• Disable 12-bit lossless JPEG processing if not required by your application
• Implement preprocessing validation to reject 12-bit JPEG images from untrusted sources
• Use alternative JPEG libraries that are not affected until patches can be applied
• Deploy web application firewalls or content filters to inspect and block malicious image uploads

# Check current libjpeg-turbo version on Linux systems
rpm -qa | grep libjpeg-turbo
# or
dpkg -l | grep libjpeg-turbo

# Update on Red Hat/CentOS/Fedora
sudo dnf update libjpeg-turbo

# Update on Debian/Ubuntu
sudo apt-get update && sudo apt-get upgrade libjpeg-turbo-progs