CVE-2025-2752: Assimp Out-of-Bounds Read Vulnerability

CVE-2025-2752 Overview

A vulnerability has been identified in Open Asset Import Library (Assimp) version 5.4.3, affecting the fast_atoreal_move function within the include/assimp/fast_atof.h header file. This out-of-bounds read vulnerability is triggered through the CSM File Handler component when processing maliciously crafted CSM files. The vulnerability allows remote attackers to potentially cause information disclosure or application crashes by supplying specially crafted input files.

Critical Impact

Remote attackers can exploit this out-of-bounds read vulnerability through malicious CSM files, potentially leading to information disclosure or denial of service conditions in applications using the Assimp library.

Affected Products

• Open Asset Import Library (Assimp) version 5.4.3
• Applications and software integrating Assimp 5.4.3 for 3D model import functionality

Discovery Timeline

• 2025-03-25 - CVE-2025-2752 published to NVD
• 2025-07-17 - Last updated in NVD database

Technical Details for CVE-2025-2752

Vulnerability Analysis

This vulnerability is classified as an out-of-bounds read (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw exists in the fast_atoreal_move function, which is a performance-optimized floating-point number parsing routine used extensively throughout the Assimp library for processing various 3D model formats.

When parsing CSM (Character Studio Motion) files, the vulnerable function fails to properly validate input boundaries before reading memory. This can result in the function reading data beyond the allocated buffer, potentially exposing sensitive memory contents or causing the application to crash.

The network attack vector indicates that exploitation can occur remotely when a victim application processes a malicious CSM file, such as through a web application that accepts user-uploaded 3D models or when opening files from untrusted sources.

Root Cause

The root cause of this vulnerability lies in insufficient bounds checking within the fast_atoreal_move function in include/assimp/fast_atof.h. The function, designed for high-performance floating-point parsing, prioritizes speed over safety and does not adequately verify that read operations remain within the bounds of the input buffer when processing numeric strings from CSM files.

Attack Vector

The attack vector is network-based, requiring user interaction. An attacker can exploit this vulnerability by:

1. Crafting a malicious CSM file containing specially formatted data that triggers the out-of-bounds read condition
2. Distributing the malicious file through various channels (email attachments, file sharing, web uploads)
3. Waiting for a victim to open or process the file using an application that incorporates the vulnerable Assimp library

The vulnerability has been publicly disclosed, and technical details are available in the GitHub issue #6013. Applications that automatically process uploaded 3D model files are particularly at risk.

Detection Methods for CVE-2025-2752

Indicators of Compromise

• Unexpected application crashes when processing CSM files
• Memory access violations or segmentation faults in applications using Assimp
• Abnormal CSM files with malformed numeric data in file headers or animation data sections

Detection Strategies

• Implement file integrity monitoring for CSM file processing workflows
• Use memory sanitizers (AddressSanitizer, Valgrind) during development and testing to detect out-of-bounds reads
• Monitor application logs for crashes related to the Assimp library or CSM file parsing
• Deploy endpoint detection solutions capable of identifying malformed 3D model files

Monitoring Recommendations

• Enable crash reporting and analysis for applications using the Assimp library
• Monitor network traffic for downloads of potentially malicious CSM files from untrusted sources
• Implement logging for all 3D file import operations to track potentially exploitative file submissions

How to Mitigate CVE-2025-2752

Immediate Actions Required

• Identify all applications and systems using Open Asset Import Library (Assimp) version 5.4.3
• Restrict processing of CSM files from untrusted sources until a patch is applied
• Monitor the Assimp GitHub repository for updates and patches addressing this vulnerability
• Consider implementing input validation and file sanitization before passing CSM files to the Assimp library

Patch Information

At the time of publication, organizations should monitor the official Assimp GitHub repository for security patches addressing this vulnerability. The issue has been tracked in GitHub Issue #6013 and additional details are available through VulDB.

Workarounds

• Disable CSM file import functionality if not required by your application
• Implement strict file type validation before processing with Assimp
• Sandbox applications that process untrusted 3D model files to limit potential impact
• Use compile-time security features (ASLR, stack canaries) to reduce exploitation impact

# Example: Compile with AddressSanitizer for detection during testing
g++ -fsanitize=address -g your_assimp_application.cpp -lassimp -o app_with_asan

# Example: Run application with memory sanitizer
ASAN_OPTIONS=detect_oob_access=1 ./app_with_asan input.csm