Assimp CVE-2026-19967

Exploitation requires that a user passively interact with a malicious file - specifically, that the target application calls Assimp's file parsing pipeline on an attacker-supplied 3D model containing a crafted compressed block (UI:P per CVSS 4.0). No authentication or privileges are required on the attacker's side (PR:N). The application must process the compressed format path that routes through Assimp::Compression::decompressBlock; applications that only handle uncompressed 3D formats may not trigger the vulnerable code path. Exploitation is limited by the need to social-engineer the victim into opening the malicious file, and by the fact that the C/I/A impact is rated Low in the CVSS 4.0 vector, suggesting reliable code execution may not be trivially achievable from the overflow alone depending on heap layout. Non-default mitigations such as ASLR and heap hardening on the host OS reduce but do not eliminate risk.

The CVSS 4.0 base score of 5.3 reflects a moderate severity with AV:N/AC:L/AT:N/PR:N/UI:P and uniformly Low C/I/A impacts on the vulnerable system, suggesting real-world exploitation is constrained by the passive user interaction requirement (UI:P - a user must open a malicious file) and the limited per-component impact. No EPSS score was provided in the input data, so exploitation probability cannot be independently quantified. The vulnerability is not listed in the CISA KEV catalog, indicating no confirmed active exploitation at time of analysis. However, the public availability of a POC archive (poc.zip via GitHub) materially lowers exploitation effort and makes opportunistic attacks more plausible. The most significant risk amplifier is the absence of a vendor patch and the lack of a vendor response to the disclosure - defenders cannot remediate through an official channel. The real-world risk is highest for applications that allow end-users to open arbitrary 3D model files from untrusted sources (e.g., game mod loaders, online asset converters, collaborative 3D editors).

An attacker crafts a malicious 3D model file with specially constructed compressed data blocks designed to overflow the heap buffer in decompressBlock, then distributes it via a file-sharing platform, email, or asset marketplace. When a victim using an Assimp-powered application (game engine, 3D editor, asset pipeline tool) opens the file, the parser triggers the overflow, corrupting heap metadata. A public POC archive (poc.zip) has been released, meaning the triggering technique is already documented and reproducible.