CVE-2026-41254: Littlecms Integer Overflow Vulnerability

CVE-2026-41254 Overview

CVE-2026-41254 is an integer overflow vulnerability in Little CMS (lcms2), a widely-used open source color management library. The vulnerability exists in the CubeSize calculation within cmslut.c, where an overflow check is incorrectly performed after the multiplication operation rather than before. This timing flaw allows the overflow to occur before validation, potentially leading to denial of service conditions when processing maliciously crafted color profiles.

Critical Impact

This network-accessible vulnerability allows remote attackers to cause denial of service conditions by exploiting the integer overflow in color profile processing, affecting applications that rely on Little CMS for color management.

Affected Products

• Little CMS (lcms2) through version 2.18
• Applications and libraries utilizing Little CMS for color management
• Image processing software that embeds lcms2

Discovery Timeline

• 2026-04-18 - CVE CVE-2026-41254 published to NVD
• 2026-04-22 - Last updated in NVD database

Technical Details for CVE-2026-41254

Vulnerability Analysis

The vulnerability in Little CMS stems from an integer overflow condition in the CubeSize function located in cmslut.c. The core issue is a classic integer overflow pattern where the bounds check occurs at the wrong point in the execution flow. When processing color lookup tables (CLUTs), the code performs a multiplication operation that can result in an integer overflow. The problem is that the validation logic intended to catch oversized values executes after the multiplication has already completed, meaning the overflow has already occurred and wrapped around to a smaller value, bypassing the intended safety check.

This vulnerability affects the availability of systems processing untrusted ICC color profiles or other color management data through Little CMS. When exploited, the overflow can lead to improper memory allocation sizes, causing the application to crash or become unresponsive.

Root Cause

The root cause is classified under CWE-696 (Incorrect Behavior Order: Early Validation) and CWE-190 (Integer Overflow or Wraparound). The fundamental flaw is that the overflow check in cmslut.c validates the result of the multiplication rather than checking whether the multiplication itself would overflow before performing it. This incorrect ordering means that by the time the check runs, the damage is already done—the integer has wrapped around to a smaller value that may pass validation but represents corrupted data.

Attack Vector

The attack vector is network-based, requiring no privileges or user interaction. An attacker can exploit this vulnerability by:

1. Crafting a malicious color profile with carefully calculated values designed to trigger the integer overflow
2. Delivering this profile to a target application that uses Little CMS for color processing
3. When the application parses the profile and calculates the CubeSize, the multiplication overflows
4. The post-multiplication check fails to catch the invalid state
5. Subsequent operations using the corrupted size value lead to denial of service

The vulnerability is exploited through the processing of ICC color profiles or similar color management data structures. Applications that process images with embedded color profiles from untrusted sources (web browsers, image viewers, email clients) are particularly at risk.

Detection Methods for CVE-2026-41254

Indicators of Compromise

• Application crashes during color profile processing, particularly when handling untrusted or externally-sourced images
• Memory allocation failures or unusual allocation patterns in processes using Little CMS
• Error logs showing failures in lcms2 color management operations or cmslut.c related functions
• Unusual process terminations in image processing or rendering workflows

Detection Strategies

• Monitor for abnormal termination patterns in applications known to use Little CMS (lcms2) for color management
• Implement file scanning for color profiles with abnormally large or suspicious CLUT dimension values
• Deploy application-level monitoring to detect crashes specifically in color management code paths
• Use memory protection tools to identify overflow conditions in lcms2-dependent processes

Monitoring Recommendations

• Enable crash reporting and analysis for applications utilizing Little CMS to identify exploitation attempts
• Monitor system logs for repeated failures in image processing operations that may indicate attack probing
• Implement file integrity monitoring on systems processing high volumes of untrusted images or color profiles
• Track resource consumption anomalies in services that handle color management operations

How to Mitigate CVE-2026-41254

Immediate Actions Required

• Update Little CMS (lcms2) to a patched version that addresses the integer overflow in CubeSize
• Restrict processing of ICC color profiles from untrusted sources until patching is complete
• Implement input validation at the application level to reject profiles with suspicious dimension values
• Consider temporarily disabling color management features in critical applications if updates cannot be applied immediately

Patch Information

The Little CMS maintainers have released patches addressing this vulnerability. Two commits have been published to fix the integer overflow:

• GitHub Commit da6110b1d14abc394633a388209abd5ebedd7ab0
• GitHub Commit e0641b1828d0a1af5ecb1b11fe22f24fceefd4bc

Organizations should apply these patches immediately or upgrade to a version of Little CMS that incorporates these fixes. For additional technical details, refer to the GitHub Security Advisory GHSA-4xp6-rcgg-m9qq and the OpenWall OSS Security Discussion.

Workarounds

• Implement pre-processing validation to reject color profiles with CLUT dimensions that could cause integer overflow when multiplied
• Use application sandboxing to isolate color management operations and limit the impact of potential crashes
• Temporarily configure applications to skip embedded color profile processing for untrusted content
• Deploy network-level filtering to inspect and quarantine files containing suspicious ICC profile structures