CVE-2025-2152: Assimp Heap-Based Buffer Overflow Flaw

CVE-2025-2152 Overview

A critical heap-based buffer overflow vulnerability has been discovered in Open Asset Import Library (Assimp) version 5.4.3. This vulnerability affects the function Assimp::BaseImporter::ConvertToUTF8 within the file BaseImporter.cpp of the File Handler component. The manipulation of input data leads to a heap-based buffer overflow condition that can be triggered remotely. The exploit has been publicly disclosed and may be actively used by threat actors.

Critical Impact

This heap-based buffer overflow vulnerability in a widely-used 3D asset import library could allow remote attackers to execute arbitrary code or cause denial of service by providing maliciously crafted asset files.

Affected Products

• Open Asset Import Library (Assimp) version 5.4.3
• Applications and game engines utilizing Assimp for 3D model import
• Development environments integrating Assimp as a dependency

Discovery Timeline

• 2025-03-10 - CVE-2025-2152 published to NVD
• 2025-03-13 - Last updated in NVD database

Technical Details for CVE-2025-2152

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-787 (Out-of-bounds Write). The flaw resides in the Assimp::BaseImporter::ConvertToUTF8 function, which handles character encoding conversion during file import operations.

When processing specially crafted 3D asset files, the function fails to properly validate the size of input data before copying it into a heap-allocated buffer. This allows an attacker to overflow the buffer boundaries, potentially corrupting adjacent heap memory structures. The vulnerability can be exploited remotely by convincing a user to open a malicious 3D model file, or by targeting applications that automatically process uploaded asset files.

The network attack vector combined with no authentication requirements makes this vulnerability particularly concerning for web-based 3D asset processing services and content management systems that utilize Assimp.

Root Cause

The root cause is insufficient bounds checking in the ConvertToUTF8 function within BaseImporter.cpp. When converting character encodings, the function does not adequately verify that the destination buffer has sufficient capacity to hold the converted data, leading to a classic heap-based buffer overflow condition.

Attack Vector

The attack can be initiated remotely by providing a maliciously crafted 3D model file to any application utilizing the vulnerable Assimp library. The attacker does not require authentication, but user interaction is needed to trigger the vulnerability—typically by opening or importing the malicious file. Successful exploitation could lead to arbitrary code execution in the context of the application processing the file, or denial of service through application crash.

The vulnerability mechanism operates through the ConvertToUTF8 function which processes character data from imported files. When malformed input is provided, the insufficient validation allows heap memory corruption. For detailed technical analysis, refer to the GitHub Issue #6027 where the vulnerability was disclosed.

Detection Methods for CVE-2025-2152

Indicators of Compromise

• Unexpected application crashes when processing 3D model files (FBX, OBJ, GLTF, etc.)
• Memory access violations or heap corruption errors in Assimp-dependent applications
• Suspicious 3D asset files with abnormal character encoding patterns or malformed headers
• Process memory anomalies indicating heap spray or overflow exploitation attempts

Detection Strategies

• Monitor for crashes in applications using Assimp library, particularly during file import operations
• Implement file integrity checks and sandboxed processing for untrusted 3D asset files
• Deploy runtime memory protection solutions that can detect heap overflow attempts
• Use static analysis tools to identify Assimp version 5.4.3 in software dependencies

Monitoring Recommendations

• Enable verbose logging for 3D asset processing pipelines to capture file handling errors
• Monitor system logs for segmentation faults or access violations in Assimp-dependent processes
• Implement network monitoring for suspicious file uploads targeting 3D asset processing endpoints
• Track dependency versions across development and production environments for vulnerable Assimp installations

How to Mitigate CVE-2025-2152

Immediate Actions Required

• Audit all applications and build pipelines for usage of Assimp version 5.4.3
• Implement input validation and file type verification before processing 3D assets
• Consider sandboxing or isolating 3D asset processing in restricted environments
• Block or quarantine untrusted 3D model files until patches are available

Patch Information

At the time of publication, users should monitor the official Assimp GitHub repository for security patches addressing this vulnerability. Check for updates beyond version 5.4.3 that include fixes for the ConvertToUTF8 function in BaseImporter.cpp. For tracking and additional context, refer to VulDB #299063.

Workarounds

• Implement strict file validation and sanitization before passing files to Assimp
• Run Assimp processing in sandboxed containers with limited privileges and memory constraints
• Disable or restrict untrusted file import functionality in affected applications
• Consider alternative 3D asset import libraries until a patched version is released

# Configuration example - Restrict file processing permissions
# Run Assimp-dependent applications with reduced privileges
chmod 750 /path/to/assimp-application
chown appuser:appgroup /path/to/assimp-application

# Create sandboxed processing directory with restricted access
mkdir -p /var/sandbox/assimp-processing
chmod 700 /var/sandbox/assimp-processing
chown appuser:appgroup /var/sandbox/assimp-processing