CVE-2025-2754: Assimp Buffer Overflow Vulnerability

CVE-2025-2754 Overview

A critical heap-based buffer overflow vulnerability has been identified in Open Asset Import Library (Assimp) version 5.4.3. The vulnerability exists within the Assimp::AC3DImporter::ConvertObjectSection function located in the file code/AssetLib/AC/ACLoader.cpp, which is part of the AC3D File Handler component. Successful exploitation of this vulnerability could allow an attacker to trigger a heap-based buffer overflow through manipulation of specific arguments, potentially leading to code execution or denial of service.

Critical Impact

Remote attackers can exploit this heap-based buffer overflow vulnerability by crafting malicious AC3D files, potentially enabling arbitrary code execution or system crashes in applications using the Assimp library.

Affected Products

• Open Asset Import Library (Assimp) version 5.4.3
• Applications and software utilizing the Assimp library for 3D model importing
• Systems processing AC3D (.ac) file formats through Assimp

Discovery Timeline

• 2025-03-25 - CVE-2025-2754 published to NVD
• 2025-07-17 - Last updated in NVD database

Technical Details for CVE-2025-2754

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the AC3D file import functionality of the Assimp library, specifically within the ConvertObjectSection function. When processing maliciously crafted AC3D files, the function fails to properly validate input boundaries before performing memory operations, resulting in a heap-based buffer overflow condition.

The vulnerability can be triggered remotely, as an attacker can deliver a specially crafted AC3D file to a victim application that utilizes the Assimp library for 3D asset importing. The exploit has been publicly disclosed, increasing the risk of exploitation in the wild.

Root Cause

The root cause of this vulnerability stems from insufficient bounds checking within the Assimp::AC3DImporter::ConvertObjectSection function in code/AssetLib/AC/ACLoader.cpp. When parsing AC3D file content, the function does not adequately validate the size or content of certain input arguments before writing them to heap-allocated memory buffers. This lack of proper input validation allows attackers to manipulate the it argument to overflow heap memory boundaries.

Attack Vector

The attack can be launched remotely over the network. An attacker would need to craft a malicious AC3D file containing specially constructed data designed to trigger the buffer overflow when processed by the vulnerable function. The attack requires user interaction, as a victim must open or process the malicious file using an application that incorporates the Assimp library.

The exploitation chain typically involves:

1. Crafting a malicious AC3D file with overflow-triggering payload
2. Delivering the file to a victim through various means (email attachment, web download, etc.)
3. Victim application processes the file using the vulnerable Assimp library
4. Heap-based buffer overflow is triggered during the ConvertObjectSection parsing

The vulnerability manifests in the ConvertObjectSection function when processing malformed AC3D file data. Technical details regarding the specific overflow condition can be found in the GitHub Issue #6015 filed against the Assimp repository.

Detection Methods for CVE-2025-2754

Indicators of Compromise

• Unexpected crashes or memory corruption errors in applications using Assimp library
• Abnormal memory allocation patterns when processing AC3D files
• Application logs showing errors related to ACLoader.cpp or ConvertObjectSection
• Suspicious AC3D files with malformed or oversized object section data

Detection Strategies

• Monitor for crashes in applications utilizing the Assimp library, particularly during AC3D file processing
• Implement file integrity monitoring for AC3D files being processed by vulnerable applications
• Deploy memory protection mechanisms such as ASLR and DEP to detect exploitation attempts
• Use application sandboxing to contain potential exploitation of the vulnerability

Monitoring Recommendations

• Enable detailed logging for applications using Assimp to capture file processing errors
• Monitor endpoint protection solutions for heap corruption or buffer overflow alerts
• Track file access patterns for AC3D file types in environments with vulnerable Assimp versions
• Review VulDB entry #300859 for updated threat intelligence

How to Mitigate CVE-2025-2754

Immediate Actions Required

• Update Assimp library to the latest version that addresses this vulnerability
• Restrict processing of untrusted AC3D files until patching is complete
• Implement input validation for AC3D files before processing with Assimp
• Consider temporarily disabling AC3D file support if not critical to operations

Patch Information

Organizations should monitor the official Assimp GitHub repository for security updates addressing this vulnerability. The issue has been tracked in GitHub Issue #6015. Check for patches or updated versions of the Assimp library that resolve the heap-based buffer overflow in the ConvertObjectSection function.

Workarounds

• Disable AC3D file import functionality in applications if not required for business operations
• Implement strict input validation to reject potentially malicious AC3D files before processing
• Deploy application sandboxing to isolate Assimp processing from critical system resources
• Use memory-safe runtime protections (ASLR, DEP, stack canaries) to mitigate exploitation impact

# Example: Disable AC3D importer at compile time (if building from source)
cmake -DASSIMP_BUILD_AC_IMPORTER=OFF ..