CVE-2026-21491: iccDEV Buffer Overflow Vulnerability

CVE-2026-21491 Overview

A heap-based buffer overflow vulnerability has been identified in iccDEV, a library and toolset for interaction, manipulation, and application of International Color Consortium (ICC) color management profiles. The vulnerability affects the CIccTagTextDescription class, specifically in the Unicode buffer handling routines. When processing maliciously crafted ICC color profiles, the library fails to properly validate buffer sizes, leading to a heap-based buffer overflow condition that can result in denial of service and potential information disclosure.

Critical Impact

Local attackers can exploit this vulnerability to cause application crashes and potentially leak sensitive memory contents through specially crafted ICC color profiles. User interaction is required as the victim must open or process a malicious ICC profile.

Affected Products

• iccDEV versions prior to 2.3.1.2
• Applications and software using the iccDEV library for ICC profile processing
• Systems processing untrusted ICC color profiles

Discovery Timeline

• 2026-01-06 - CVE CVE-2026-21491 published to NVD
• 2026-01-08 - Last updated in NVD database

Technical Details for CVE-2026-21491

Vulnerability Analysis

This vulnerability is classified as CWE-122 (Heap-based Buffer Overflow). The flaw exists in the GetUnicodeBuffer function within the CIccTagTextDescription class in IccProfLib/IccTagBasic.cpp. The function allocates memory for Unicode text buffers without properly accounting for NULL termination requirements.

When processing ICC profiles containing text description tags with Unicode content, the function performed an insufficient size check. The original code compared m_nUnicodeSize < nSize, but failed to account for the required NULL terminator space. This off-by-one error allowed buffer operations to write beyond the allocated heap memory, causing heap corruption.

The vulnerability requires local access and user interaction—an attacker must convince a victim to open a maliciously crafted ICC profile. Successful exploitation can lead to application crashes (denial of service) and limited confidentiality impact through potential memory disclosure.

Root Cause

The root cause is an improper boundary condition check in the GetUnicodeBuffer method. The original implementation failed to properly account for NULL termination bytes when calculating buffer allocation requirements. The size comparison m_nUnicodeSize < nSize should have been m_nUnicodeSize < (nSize+2) to accommodate the double-byte NULL terminator required for Unicode strings. Additionally, the reallocation size calculation (nSize+1)*sizeof(icUInt16Number) was insufficient, requiring correction to (nSize+2)*sizeof(icUInt16Number).

Attack Vector

The attack vector requires local access where an attacker crafts a malicious ICC color profile containing specially designed text description tags. When a victim opens or processes this malformed profile using an application that relies on the vulnerable iccDEV library, the heap buffer overflow is triggered. The attacker can control the overflow data through the crafted profile's Unicode text content, potentially causing denial of service through memory corruption or application crash.

// Security patch in IccProfLib/IccTagBasic.cpp
// Source: https://github.com/InternationalColorConsortium/iccDEV/commit/7c2cb719a9de1c00844e457e070d657314383ee3

  */
 icUInt16Number *CIccTagTextDescription::GetUnicodeBuffer(icUInt32Number nSize)
 {
-  if (m_nUnicodeSize < nSize) {
-    m_uzUnicodeText = (icUInt16Number*)icRealloc(m_uzUnicodeText, (nSize+1)*sizeof(icUInt16Number));
+  if (m_nUnicodeSize < (nSize+2)) { // test for existing size must include the NULL termination!
+    m_uzUnicodeText = (icUInt16Number*)icRealloc(m_uzUnicodeText, (nSize+2)*sizeof(icUInt16Number));

     m_uzUnicodeText[nSize] = 0;
+    m_uzUnicodeText[nSize+1] = 0;

-    m_nUnicodeSize = nSize;
+    m_nUnicodeSize = nSize+2;
   }

   return m_uzUnicodeText;

Source: GitHub Commit Update

Detection Methods for CVE-2026-21491

Indicators of Compromise

• Unexpected application crashes when processing ICC color profiles
• Heap corruption or memory allocation errors in applications using iccDEV library
• Unusual memory access patterns or segmentation faults related to ICC profile operations
• Core dumps indicating buffer overflow conditions in IccTagBasic.cpp or related modules

Detection Strategies

• Deploy application crash monitoring to detect segmentation faults in ICC profile processing applications
• Implement file integrity monitoring for ICC profile files in monitored directories
• Use memory debugging tools (Valgrind, AddressSanitizer) in development and testing environments to detect heap overflows
• Monitor for anomalous ICC profile files with oversized or malformed text description tags

Monitoring Recommendations

• Enable detailed logging for applications that process ICC color profiles
• Configure SentinelOne to monitor for heap corruption indicators in processes using iccDEV
• Implement file quarantine policies for ICC profiles from untrusted sources
• Review application logs for memory allocation failures related to Unicode buffer operations

How to Mitigate CVE-2026-21491

Immediate Actions Required

• Upgrade iccDEV library to version 2.3.1.2 or later immediately
• Audit applications using iccDEV and prioritize updates for those processing untrusted ICC profiles
• Restrict processing of ICC profiles from untrusted or unknown sources until patching is complete
• Consider implementing input validation for ICC profile sizes before processing

Patch Information

The vulnerability has been patched in iccDEV version 2.3.1.2. The fix addresses the buffer allocation issue by properly accounting for NULL termination requirements in the Unicode buffer. Two commits were applied to resolve this vulnerability:

• GitHub Commit Update - Fixes TagTextDescription buffer allocation
• GitHub Commit Change - Additional validation for 3DLUT channel counts

The complete security advisory is available at the GitHub Security Advisory.

Workarounds

• No known workarounds are available for this vulnerability; patching to version 2.3.1.2 is the only remediation
• As a temporary measure, avoid processing ICC profiles from untrusted sources
• Implement network segmentation to isolate systems that must process untrusted ICC profiles
• Consider sandboxing applications that process ICC profiles to limit potential impact

# Update iccDEV to patched version
git clone https://github.com/InternationalColorConsortium/iccDEV.git
cd iccDEV
git checkout v2.3.1.2
mkdir build && cd build
cmake ..
make && sudo make install