CVE-2026-4775: libtiff Library RCE Vulnerability

CVE-2026-4775 Overview

A signed integer overflow vulnerability has been discovered in the libtiff library, specifically within the putcontig8bitYCbCr44tile function. A remote attacker can exploit this flaw by providing a specially crafted TIFF file, triggering an out-of-bounds heap write due to incorrect memory pointer calculations. Successful exploitation may result in denial of service through application crash or potentially arbitrary code execution.

Critical Impact

This integer overflow vulnerability enables heap-based memory corruption that can be triggered through malicious TIFF files, potentially allowing attackers to execute arbitrary code or crash applications processing images.

Affected Products

• libtiff library (all versions prior to patch)
• Applications and systems utilizing the libtiff library for TIFF image processing
• Linux distributions including Red Hat Enterprise Linux that bundle libtiff

Discovery Timeline

• 2026-03-24 - CVE-2026-4775 published to NVD
• 2026-03-24 - Last updated in NVD database

Technical Details for CVE-2026-4775

Vulnerability Analysis

This vulnerability (CWE-190: Integer Overflow or Wraparound) exists within the putcontig8bitYCbCr44tile function of the libtiff library. The function processes YCbCr color space data with 4:4:4 chroma subsampling during TIFF file handling. When processing specially crafted TIFF files, a signed integer overflow occurs during memory allocation or pointer arithmetic calculations.

The flaw enables an attacker to manipulate image dimension parameters or tile configuration values in a way that causes the signed integer overflow. This overflow subsequently leads to incorrect memory pointer calculations, resulting in an out-of-bounds heap write condition. The corruption of heap memory can cause application instability, denial of service through crashes, or potentially allow arbitrary code execution if an attacker can control the overwritten memory contents.

The local attack vector requires user interaction—typically opening or processing a malicious TIFF file. This makes the vulnerability particularly dangerous in scenarios involving image processing pipelines, document management systems, or applications that automatically process uploaded images.

Root Cause

The root cause is improper handling of signed integer arithmetic within the putcontig8bitYCbCr44tile function. When processing TIFF files with specially crafted dimension or tile parameters, the signed integer values used in memory size calculations or pointer arithmetic can overflow, wrapping around to unexpected values. This results in memory operations being performed at incorrect locations, causing heap buffer corruption.

Attack Vector

The attack requires local access with user interaction to process a malicious TIFF file. An attacker would craft a TIFF file with manipulated header values or tile parameters designed to trigger the signed integer overflow condition. The malicious file could be delivered through various means including email attachments, web downloads, or file sharing platforms. When a vulnerable application processes the file, the integer overflow corrupts heap memory, potentially leading to code execution or denial of service.

The vulnerability manifests in the boundary calculation and memory pointer arithmetic within the putcontig8bitYCbCr44tile function. When processing YCbCr image data with specific malformed parameters, the signed integer overflow causes subsequent heap operations to write beyond allocated buffer boundaries. For detailed technical analysis, see the Red Hat CVE-2026-4775 Advisory and Red Hat Bug Report #2450768.

Detection Methods for CVE-2026-4775

Indicators of Compromise

• Unexpected application crashes when processing TIFF image files
• Memory corruption errors or segmentation faults in applications using libtiff
• Abnormal heap allocation patterns in image processing applications
• Core dumps indicating heap buffer overflow in libtiff-related functions

Detection Strategies

• Monitor system and application logs for crashes involving libtiff or TIFF processing components
• Implement file integrity monitoring on libtiff library files to detect unauthorized modifications
• Deploy runtime memory protection tools such as AddressSanitizer (ASan) in development and testing environments
• Use endpoint detection solutions like SentinelOne to identify exploitation attempts and memory corruption events

Monitoring Recommendations

• Enable crash reporting and analysis for applications that process image files
• Monitor for unusual TIFF file uploads or downloads, particularly files with abnormal header values
• Implement network-based file inspection to detect potentially malicious TIFF files before processing
• Review application logs for repeated failures or errors related to image processing

How to Mitigate CVE-2026-4775

Immediate Actions Required

• Update libtiff library to the latest patched version provided by your distribution vendor
• Restrict processing of untrusted TIFF files until patches are applied
• Review and limit applications that automatically process TIFF images from untrusted sources
• Apply vendor security updates for affected Linux distributions, including Red Hat Enterprise Linux

Patch Information

Consult your distribution vendor for available security patches addressing this vulnerability. Red Hat has published advisory information regarding this flaw. System administrators should apply updates through their standard package management systems. See the Red Hat CVE-2026-4775 Advisory for specific patch guidance and affected package versions.

Workarounds

• Disable or restrict TIFF file processing in affected applications where possible
• Implement strict input validation for TIFF files before processing, including file size and dimension checks
• Use sandboxed or containerized environments for processing untrusted image files
• Configure web application firewalls to inspect and filter potentially malicious TIFF uploads

# Example: Check installed libtiff version on Red Hat-based systems
rpm -qa | grep libtiff

# Update libtiff package
sudo yum update libtiff

# Verify the updated version
rpm -q libtiff