CVE-2023-25433: Libtiff Buffer Overflow Vulnerability

CVE-2023-25433 Overview

CVE-2023-25433 is a heap buffer overflow vulnerability in libtiff version 4.5.0, specifically affecting the tiffcrop utility. The vulnerability stems from incorrect buffer size management after the rotateImage() function executes in /libtiff/tools/tiffcrop.c at line 8499. When exploited, this flaw causes a heap-buffer-overflow condition and segmentation fault (SEGV), leading to denial of service.

Critical Impact

Attackers can craft malicious TIFF files that, when processed by tiffcrop, trigger a heap buffer overflow causing application crashes and potential denial of service conditions.

Affected Products

• libtiff 4.5.0

Discovery Timeline

• 2023-06-29 - CVE-2023-25433 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2023-25433

Vulnerability Analysis

This vulnerability is classified as CWE-120 (Buffer Copy without Checking Size of Input). The core issue lies in the tiffcrop tool's image rotation functionality, where the buffer size is not properly recalculated after the rotateImage() function completes its operation. When processing specially crafted TIFF images, the tool continues to operate with an outdated buffer size assumption, leading to out-of-bounds memory access on the heap.

The attack requires local access and user interaction, meaning an attacker must convince a victim to process a malicious TIFF file using the vulnerable tiffcrop utility. While this limits the attack surface, the vulnerability can reliably cause application crashes, making it effective for denial of service scenarios.

Root Cause

The root cause of CVE-2023-25433 is improper buffer management in the tiffcrop.c source file. After the rotateImage() function processes an image, the buffer size variable is not updated to reflect the new dimensions of the rotated image. Subsequent operations then use the incorrect buffer size, causing heap memory corruption when the actual data exceeds the originally allocated bounds.

Attack Vector

The attack vector requires local access to the system and user interaction to trigger. An attacker would need to:

1. Craft a malicious TIFF image file designed to exploit the buffer size miscalculation
2. Convince a user or automated process to run tiffcrop with rotation operations on the malicious file
3. The vulnerable code path is triggered when image rotation is performed, causing the heap buffer overflow

The vulnerability manifests specifically in the tiffcrop utility's rotation handling code. When the rotateImage() function completes, buffer dimensions change but the size tracking variable remains unchanged. Subsequent memory operations based on this incorrect size cause out-of-bounds heap access, resulting in a segmentation fault. For detailed technical analysis, see the GitLab Issue #520 and GitLab Merge Request #467.

Detection Methods for CVE-2023-25433

Indicators of Compromise

• Unexpected crashes or segmentation faults when running tiffcrop with rotation operations
• Core dumps or crash reports indicating heap corruption in libtiff-related processes
• Unusual TIFF files with malformed or unexpected dimension metadata being processed

Detection Strategies

• Monitor for abnormal termination of processes using libtiff libraries, particularly tiffcrop
• Implement file integrity monitoring on systems processing TIFF files from untrusted sources
• Deploy memory corruption detection tools (such as AddressSanitizer) in development and testing environments to catch heap-buffer-overflow conditions

Monitoring Recommendations

• Enable crash reporting and analysis for image processing workflows that utilize tiffcrop
• Log all tiffcrop invocations with rotation parameters for forensic analysis
• Monitor system logs for SEGV signals associated with libtiff processes

How to Mitigate CVE-2023-25433

Immediate Actions Required

• Update libtiff to a patched version that addresses the buffer size tracking issue
• Avoid using tiffcrop rotation features on untrusted TIFF files until patched
• Implement input validation to reject potentially malicious TIFF files before processing
• Consider using alternative tools for TIFF manipulation until patches are applied

Patch Information

The libtiff project has addressed this vulnerability through GitLab Merge Request #467. Organizations should upgrade to a fixed version of libtiff that incorporates this patch. Debian-based systems can reference the Debian LTS Security Announcement for distribution-specific patching guidance.

Workarounds

• Disable or remove the tiffcrop utility if rotation functionality is not required
• Process only trusted TIFF files from verified sources
• Run tiffcrop in a sandboxed environment to contain potential crashes
• Use alternative image processing tools that are not affected by this vulnerability

# Check libtiff version for vulnerable installations
tiffinfo -v 2>&1 | head -1

# Restrict tiffcrop execution to trusted users only
chmod 750 /usr/bin/tiffcrop

# Update libtiff via package manager (Debian/Ubuntu example)
sudo apt-get update && sudo apt-get install --only-upgrade libtiff-tools