Assimp CVE-2026-10229

The target application must explicitly invoke Assimp's Half-Life 1 MDL Loader - this code path is only reached when processing files in the HL1 MDL format, which is a non-default, legacy-format-specific branch not activated for other 3D file types. The attacker must have local system access (AV:L per CVSS) with at least low-privilege credentials (PR:L) to supply or place the crafted MDL file where the application will ingest it. Remote unauthenticated exploitation is not possible per the CVSS vector. Exploitation is further limited to the scope of the vulnerable process (S:U), meaning even a successful overflow does not automatically affect other processes or escalate to system level. The impact ceiling is partial across all three pillars (C:L/I:L/A:L), constraining the blast radius absent a chained privilege escalation.

The CVSS 3.1 base score of 5.3 (Medium) reflects a local, low-complexity, low-privilege attack with no user interaction required and an unscoped, partial-impact outcome (C:L/I:L/A:L). The E:P temporal modifier confirms proof-of-concept exploit code is publicly available, incrementally elevating real-world risk. No EPSS score was provided in the input data, so exploitation probability cannot be quantitatively benchmarked. The vulnerability is not listed in the CISA KEV catalog, meaning no confirmed mass or targeted exploitation has been observed. The Assimp maintainers have classified this as a bug rather than a security vulnerability, which may delay an official patch. Real-world impact is constrained: exploitation requires local system access, low-privilege credentials, and the target application must actively process attacker-supplied HL1 MDL files. This makes opportunistic exploitation unlikely but leaves developer workstations, CI/CD asset pipelines, and game modding toolchains at meaningful risk if they process externally sourced model files.

A local attacker with low-privilege credentials on a developer workstation or asset-pipeline server submits a specially crafted Half-Life 1 MDL file to an application that uses Assimp for model ingestion - such as a game engine editor, a batch 3D asset converter, or a modding tool. When the application calls HL1MDLLoader::read_meshes to parse the file, the lack of proper bounds checking triggers a heap-based buffer overflow, corrupting adjacent heap memory. A publicly available proof-of-concept (poc.zip, linked via GitHub attachment in the references) demonstrates the triggering condition; the partial C/I/A impact suggests the overflow can at minimum crash the process and may enable limited memory read/write primitives depending on heap layout.