CVE-2026-6192: OpenJPEG Buffer Overflow Vulnerability

CVE-2026-6192 Overview

An integer overflow vulnerability was identified in uclouvain OpenJPEG versions up to 2.5.4. This vulnerability impacts the function opj_pi_initialise_encode in the library src/lib/openjp2/pi.c. The manipulation of specific parameters leads to an integer overflow condition during memory allocation calculations. The attack must be carried out locally, requiring an attacker to have local access to the target system. The exploit is publicly available and might be used in attacks. A patch has been released to address this issue.

Critical Impact

Local attackers can trigger an integer overflow in the JPEG 2000 image encoding library, potentially causing memory corruption or denial of service conditions in applications that process malicious image files.

Affected Products

• OpenJPEG versions up to 2.5.4
• Applications and libraries that integrate OpenJPEG for JPEG 2000 image processing
• Systems using vulnerable OpenJPEG builds for image encoding operations

Discovery Timeline

• April 13, 2026 - CVE-2026-6192 published to NVD
• April 13, 2026 - Last updated in NVD database

Technical Details for CVE-2026-6192

Vulnerability Analysis

The vulnerability exists in the opj_pi_initialise_encode() function within the OpenJPEG library's packet iterator implementation. During the initialization of the encoding process, the function calculates memory requirements for the include array by multiplying l_tcp->numlayers by l_step_l. Without proper overflow checking, this multiplication can exceed the maximum value representable by the integer type, resulting in a smaller-than-expected memory allocation. This integer overflow condition (CWE-189) can lead to subsequent heap-based buffer overflows when the undersized buffer is used, potentially causing application crashes or enabling memory corruption attacks.

Root Cause

The root cause is the absence of integer overflow validation before performing arithmetic operations used to calculate buffer sizes. The original code directly multiplied l_tcp->numlayers and l_step_l without verifying that the result would fit within the bounds of the target integer type. When processing specially crafted JPEG 2000 images with extreme layer or step values, this multiplication can wrap around, producing a small value that leads to insufficient memory allocation.

Attack Vector

This is a local attack vector vulnerability. An attacker with local system access must craft a malicious JPEG 2000 image file with parameters designed to trigger the integer overflow condition. When a vulnerable application processes this image using OpenJPEG's encoding functionality, the overflow occurs during the opj_pi_initialise_encode() function execution. The attacker could potentially leverage this to cause denial of service through application crashes or potentially achieve more severe impacts through memory corruption.

// Security patch from commit 839936aa33eb8899bbbd80fda02796bb65068951
// Before (vulnerable):
    l_current_pi->include_size = l_tcp->numlayers * l_step_l;
    l_current_pi->include = (OPJ_INT16*) opj_calloc(l_current_pi->include_size,
                            sizeof(OPJ_INT16));

// After (fixed):
    l_current_pi->include = NULL;
    if (l_step_l <= UINT_MAX / l_tcp->numlayers) {
        l_current_pi->include_size = l_tcp->numlayers * l_step_l;
        l_current_pi->include = (OPJ_INT16*) opj_calloc(l_current_pi->include_size,
                                sizeof(OPJ_INT16));
    }
    if (!l_current_pi->include) {
        opj_free(l_tmp_data);
        opj_free(l_tmp_ptr);

Source: GitHub OpenJPEG Commit

Detection Methods for CVE-2026-6192

Indicators of Compromise

• Application crashes or unexpected termination when processing JPEG 2000 image files
• Memory allocation failures or out-of-memory errors in OpenJPEG-dependent applications
• Unusual image files with abnormally large layer or resolution level configurations

Detection Strategies

• Monitor for crashes in applications using OpenJPEG libraries with stack traces pointing to opj_pi_initialise_encode or pi.c
• Implement file integrity monitoring for OpenJPEG library files to detect unauthorized modifications
• Use static analysis tools to scan for vulnerable OpenJPEG versions in deployed software

Monitoring Recommendations

• Enable crash dump collection for applications processing JPEG 2000 images to identify potential exploitation attempts
• Monitor system logs for repeated application failures associated with image processing workflows
• Audit software inventory to identify all instances of OpenJPEG library usage across the environment

How to Mitigate CVE-2026-6192

Immediate Actions Required

• Update OpenJPEG to the patched version containing commit 839936aa33eb8899bbbd80fda02796bb65068951
• Audit systems for applications that bundle or depend on OpenJPEG versions up to 2.5.4
• Restrict local access to systems running vulnerable OpenJPEG versions until patching is complete
• Consider temporarily disabling JPEG 2000 encoding functionality if not critical to operations

Patch Information

The OpenJPEG development team has released a security patch addressing this integer overflow vulnerability. The fix adds proper overflow checking before the multiplication operation by validating that l_step_l <= UINT_MAX / l_tcp->numlayers before performing the calculation. If the check fails, the allocation is skipped and proper error handling is triggered. The patch is available via commit 839936aa33eb8899bbbd80fda02796bb65068951. Additional details can be found in the associated GitHub Issue #1619 and Pull Request #1628.

Workarounds

• Limit processing of untrusted JPEG 2000 image files until the patch can be applied
• Implement input validation to reject image files with suspicious or extreme metadata values
• Run OpenJPEG-dependent applications in sandboxed environments to limit impact of potential exploitation

# Configuration example
# Verify installed OpenJPEG version and check for vulnerable builds
pkg-config --modversion libopenjp2

# Update OpenJPEG from source with the security patch
git clone https://github.com/uclouvain/openjpeg.git
cd openjpeg
git checkout 839936aa33eb8899bbbd80fda02796bb65068951
mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
make && sudo make install