CVE-2026-34556: iccDEV Buffer Overflow Vulnerability

CVE-2026-34556 Overview

CVE-2026-34556 is a heap-buffer-overflow vulnerability affecting iccDEV, a set of libraries and tools for working with ICC color management profiles. Prior to version 2.3.1.6, the icAnsiToUtf8() function in the XML conversion path contains an out-of-bounds read vulnerability that can be triggered by processing a specially crafted ICC profile.

The vulnerability occurs because icAnsiToUtf8(std::string&, char const*) treats an input buffer as a C-string and calls operations that rely on strlen() and null-termination. AddressSanitizer reports an out-of-bounds READ of size 115 past a 114-byte heap allocation, observed during execution of the iccToXml tool.

Critical Impact

A crafted ICC profile can trigger a heap-buffer-overflow read, potentially leading to denial of service or information disclosure when processing malicious color profiles.

Affected Products

• iccDEV versions prior to 2.3.1.6
• Applications using iccDEV libraries for ICC profile processing
• The iccToXml command-line tool

Discovery Timeline

• 2026-03-31 - CVE-2026-34556 published to NVD
• 2026-04-01 - Last updated in NVD database

Technical Details for CVE-2026-34556

Vulnerability Analysis

This vulnerability is classified as CWE-125 (Out-of-bounds Read). The flaw resides in the XML conversion pathway of the iccDEV library, specifically within the icAnsiToUtf8() function. When processing ICC color profiles that are converted to XML format, the function incorrectly assumes that input data is properly null-terminated.

The root cause stems from treating arbitrary binary data within ICC profiles as null-terminated C-strings. When the icAnsiToUtf8() function receives a buffer that lacks proper null-termination, it continues reading beyond the allocated heap buffer boundaries until it encounters a null byte in adjacent memory.

Root Cause

The icAnsiToUtf8() function expects its input parameter to be a properly null-terminated string. However, when processing certain ICC profile elements during XML conversion, the function receives buffer data that may not contain a null terminator within the expected bounds. This causes string operations relying on strlen() to read past the allocated buffer, resulting in a heap-buffer-overflow read condition.

Attack Vector

The attack vector requires local access and involves supplying a maliciously crafted ICC profile to applications utilizing the iccDEV library. An attacker would need to:

1. Create a specially crafted ICC profile with malformed data in sections processed by icAnsiToUtf8()
2. Supply this profile to an application using iccDEV, such as the iccToXml tool
3. The malformed profile triggers the out-of-bounds read during XML conversion

The vulnerability does not require user interaction beyond opening the malicious file and operates without any special privileges. As documented in the security advisory, AddressSanitizer detected a read of 115 bytes past a 114-byte heap allocation, indicating the overflow reads exactly one byte beyond the buffer boundary in the reported case.

Detection Methods for CVE-2026-34556

Indicators of Compromise

• Unexpected crashes or segmentation faults when processing ICC profiles
• AddressSanitizer heap-buffer-overflow errors in applications compiled with memory sanitizers
• Abnormal memory access patterns in processes using iccDEV libraries
• Crash logs referencing icAnsiToUtf8() or XML conversion functions

Detection Strategies

• Deploy memory sanitizers (AddressSanitizer, Valgrind) in development and testing environments to detect out-of-bounds reads
• Monitor application logs for crashes during ICC profile processing operations
• Implement input validation to reject malformed ICC profiles before processing
• Use file integrity monitoring for suspicious ICC profile files in shared directories

Monitoring Recommendations

• Enable crash reporting and telemetry for applications processing ICC color profiles
• Monitor system logs for repeated crashes in iccDEV-dependent applications
• Track unusual file access patterns involving .icc or .icm profile files
• Consider sandboxing color profile processing operations to limit impact

How to Mitigate CVE-2026-34556

Immediate Actions Required

• Upgrade iccDEV to version 2.3.1.6 or later immediately
• Audit systems for applications and dependencies using vulnerable iccDEV versions
• Implement input validation for ICC profiles from untrusted sources
• Consider temporarily disabling ICC profile processing functionality if patching is delayed

Patch Information

The vulnerability has been patched in iccDEV version 2.3.1.6. The fix addresses the improper string handling in icAnsiToUtf8() to ensure proper bounds checking before performing string operations.

For detailed patch information, refer to the GitHub Pull Request #740 which contains the security fix. Additional context is available in the GitHub Security Advisory GHSA-p9wm-xfv4-43qg and the original GitHub Issue #734.

Workarounds

• Restrict ICC profile processing to trusted sources only until patching is complete
• Implement strict input validation to verify ICC profile structure before processing
• Run iccDEV-dependent applications in sandboxed environments with limited privileges
• Use memory-safe language wrappers where possible to contain potential exploitation

# Configuration example
# Verify iccDEV version to ensure patch is applied
iccDEV --version
# Expected output should show version 2.3.1.6 or higher

# Update iccDEV from source
git clone https://github.com/InternationalColorConsortium/iccDEV.git
cd iccDEV
git checkout v2.3.1.6
mkdir build && cd build
cmake ..
make && sudo make install