CVE-2026-10230: Assimp Buffer Overflow Vulnerability

CVE-2026-10230 Overview

CVE-2026-10230 is a heap-based buffer overflow [CWE-119] in the Open Asset Import Library (Assimp) versions up to 6.0.4. The flaw resides in the Assimp::MDL::HalfLife::HL1MDLLoader::read_animations function within HL1MDLLoader.cpp, part of the Half-Life 1 MDL loader component. Processing a malformed MDL model file triggers an out-of-bounds write on the heap. The issue requires local access and low privileges, and the project maintainers have tagged the report as a bug. A public exploit reference exists, but the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

Critical Impact
A local attacker supplying a crafted Half-Life 1 MDL file to an application linked against Assimp can corrupt heap memory, potentially leading to application crash or limited code execution within the loader process.

Affected Products

Assimp (Open Asset Import Library) versions up to and including 6.0.4
Applications and game engines that embed the Assimp HL1MDLLoader component
Asset pipelines and 3D content tools that parse Half-Life 1 MDL files through Assimp

Discovery Timeline

2026-06-01 - CVE-2026-10230 published to NVD
2026-06-01 - Last updated in NVD database

Technical Details for CVE-2026-10230

Vulnerability Analysis

The defect sits in the Half-Life 1 MDL loader implementation shipped with Assimp. When HL1MDLLoader::read_animations parses animation data from an MDL file, the loader writes beyond the bounds of a heap-allocated buffer. The condition is classified under [CWE-119], improper restriction of operations within the bounds of a memory buffer.

Exploitation requires the attacker to deliver a malicious MDL file to a user or service that processes it through Assimp. Because Assimp is a widely embedded import library used by game engines, modeling tools, and 3D pipelines, the attack surface extends to any product that links against the vulnerable loader. The impact is constrained to the local context where the parser executes, and the confidentiality, integrity, and availability impacts are each rated low.

Root Cause

The root cause is missing or insufficient bounds checking on values read from untrusted MDL file fields before they are used to index or write into a heap allocation in read_animations. Attacker-controlled animation metadata in the MDL header drives a write that exceeds the allocated region. Refer to GitHub Issue #6615 for the upstream report and reproduction details.

Attack Vector

The attack vector is local. An attacker must induce a user or automated process to open a crafted MDL file with an application that uses Assimp's Half-Life 1 importer. No authentication beyond standard user privileges is required, and user interaction is not needed when the loader runs in a server-side asset processing pipeline.

No verified proof-of-concept code is provided in the advisory. The mechanism involves a malformed MDL file with manipulated animation count or size fields that drive the overflow during deserialization. See the VulDB entry for CVE-2026-10230 for additional context.

Detection Methods for CVE-2026-10230

Indicators of Compromise

Crashes or abnormal terminations in processes that load .mdl files through Assimp, particularly with stack traces referencing HL1MDLLoader::read_animations.
Heap corruption signatures reported by allocator instrumentation (AddressSanitizer, glibc malloc checks) during MDL parsing.
Untrusted MDL files arriving from external sources into asset pipelines or content directories.

Detection Strategies

Inventory binaries and containers for the Assimp library and identify versions at or below 6.0.4 using software composition analysis tooling.
Run fuzz testing or sanitizer-instrumented builds against the HL1MDLLoader code path with mutated MDL samples to surface the overflow.
Hash and quarantine untrusted MDL files at ingestion points, then scan them for anomalous animation header values before passing to Assimp.

Monitoring Recommendations

Monitor process crash telemetry for applications and services that invoke Assimp, correlating faults with recently processed MDL files.
Log file ingestion events in 3D asset pipelines and alert on MDL files originating from external or low-trust sources.
Track upstream commits to the Assimp GitHub repository for the fix referenced in issue #6615.

How to Mitigate CVE-2026-10230

Immediate Actions Required

Identify all applications, services, and containers that bundle Assimp 6.0.4 or earlier and prioritize those that accept externally supplied model files.
Restrict MDL file ingestion to trusted sources and block untrusted .mdl uploads in asset pipelines until a patched build is deployed.
Run Assimp-based parsing in sandboxed or least-privilege contexts so that heap corruption is contained to a restricted process.

Patch Information

No fixed version is referenced in the published advisory at the time of NVD publication. Track the upstream Assimp GitHub repository and the discussion in GitHub Issue #6615 for the remediation commit. Once an upstream fix lands, rebuild all dependent applications against the patched release and redeploy affected containers and binaries.

Workarounds

Disable the Half-Life 1 MDL importer at build time by excluding HL1MDLLoader from the Assimp build configuration if the format is not required.
Validate MDL file structure with an external parser before handing the file to Assimp, rejecting files with inconsistent animation counts or sizes.
Execute MDL parsing within a sandbox (seccomp, AppArmor, container) that limits filesystem and network access available to the parsing process.

bash

# Configuration example: disable HL1 MDL importer when building Assimp from source
cmake -DASSIMP_BUILD_MDL_IMPORTER=OFF \
      -DASSIMP_BUILD_HL1_IMPORTER=OFF \
      -DASSIMP_BUILD_TESTS=OFF \
      -DCMAKE_BUILD_TYPE=Release \
      ..
make -j$(nproc)