CVE-2026-10197

Executive Summary

CVE-2026-10197 is a locally exploitable null pointer dereference vulnerability in the Assimp library, affecting versions up to and including 6.0.4. The flaw resides in the glTF2Importer::ImportEmbeddedTextures function within the glTF2 file handler (code/AssetLib/glTF2/glTF2Importer.cpp). An attacker with local access can trigger a null pointer dereference, leading to a denial of service (DoS) condition. The exploit has been made public, increasing the risk of targeted attacks. No patch is currently available, though a pull request is pending acceptance.

Supply Chain & Package Security

Assimp (Open Asset Import Library) is a widely used library for importing various 3D model formats. It is a dependency in many applications, including game engines, 3D modeling software, and rendering tools. This vulnerability can be exploited locally, meaning an attacker must have access to the system to trigger it. However, in supply chain scenarios, a malicious actor could craft a glTF file that, when processed by any application using the vulnerable Assimp version, causes a crash. This is particularly concerning for applications that automatically process user-uploaded 3D models.

CVSS Breakdown & Threat Level

• CVSS Score: 3.3 (Low)
• Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
• Attack Vector (AV): Local (L) - The attacker must have local access to the system.
• Attack Complexity (AC): Low (L) - No special conditions are required.
• Privileges Required (PR): None (N) - No privileges are needed.
• User Interaction (UI): None (N) - No user interaction is required.
• Scope (S): Unchanged (U) - The vulnerability does not affect other components.
• Confidentiality (C): None (N) - No data is exposed.
• Integrity (I): None (N) - No data is modified.
• Availability (A): Low (L) - The vulnerability can cause a denial of service.

Threat Level: Low. The attack requires local access, limiting its exploitability. However, the public availability of the exploit and the lack of a patch elevate the risk for systems where untrusted users have local access.

Deep Dive & Mechanics

The vulnerability is a classic null pointer dereference in the glTF2Importer::ImportEmbeddedTextures function. When processing a specially crafted glTF 2.0 file, the function fails to properly validate a pointer before dereferencing it. This occurs when the file contains embedded texture data that is malformed or missing expected fields. The function attempts to access a member of a null pointer, causing the application to crash.

Technical Flow:

1. An attacker creates a malicious glTF 2.0 file with a corrupted or missing embedded texture data structure.
2. The application loads the file using Assimp's aiImportFile or similar function.
3. The glTF2 importer parses the file and calls ImportEmbeddedTextures.
4. Inside this function, a pointer to a texture data structure is expected to be non-null, but due to the malformed input, it is null.
5. The function dereferences the null pointer, leading to a segmentation fault and application crash.

Vulnerable vs. Patched Code

Vulnerable Code (Assimp <= 6.0.4):

// code/AssetLib/glTF2/glTF2Importer.cpp
void glTF2Importer::ImportEmbeddedTextures(glTF2::Asset &asset) {
    for (auto &texture : asset.mRoot->textures) {
        // texture.mSource is assumed to be non-null
        if (texture.mSource->mimeType == "image/png") { // Null pointer dereference here
            // ...
        }
    }
}

Patched Code (Expected fix):

// code/AssetLib/glTF2/glTF2Importer.cpp
void glTF2Importer::ImportEmbeddedTextures(glTF2::Asset &asset) {
    for (auto &texture : asset.mRoot->textures) {
        // Check for null pointer before dereferencing
        if (texture.mSource != nullptr && texture.mSource->mimeType == "image/png") {
            // ...
        }
    }
}

The fix adds a null check (texture.mSource != nullptr) before accessing the mimeType member.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Local access to the target system.
• Ability to write a file to a location that will be processed by an application using Assimp.

Exploit Steps:

1. Create a malicious glTF 2.0 file with a null pointer in the embedded texture data.
2. Place the file in a location where the target application will load it (e.g., a game's asset directory, a 3D modeling software's import folder).
3. Trigger the application to load the file (e.g., by opening it or by the application automatically scanning the directory).
4. The application crashes due to the null pointer dereference.

Example Malicious glTF File (partial):

{
  "asset": {
    "version": "2.0"
  },
  "images": [
    {
      "uri": "data:image/png;base64,...",
      "mimeType": "image/png"
    }
  ],
  "textures": [
    {
      "source": null
    }
  ]
}

Blue Team

Detection:

• Monitor for crashes in applications that use Assimp.
• Look for segmentation faults or access violations in logs.
• Use file integrity monitoring to detect the introduction of new glTF files.

Mitigation:

• Restrict local access to trusted users only.
• Use application sandboxing to limit the impact of a crash.
• Apply the patch as soon as it becomes available.

Indicators of Compromise (IOCs)

• File Hashes: (Example - actual hash will vary)
  • malicious.gltf - SHA256: a1b2c3d4e5f6...
• Process Behavior:
  • Application crash with signal SIGSEGV (segmentation fault).
  • Error logs containing "null pointer" or "access violation" in the context of Assimp.
• Network: None (local vulnerability).
• Registry/File System: Presence of a glTF file with a null value for the source field in a texture object.

Detection Engineering

YARA Rule

rule CVE_2026_10197_Assimp_Null_Pointer_Dereference {
    meta:
        description = "Detects malicious glTF files exploiting CVE-2026-10197"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "CVE-2026-10197"
    strings:
        $gltf_header = "\"asset\""
        $null_source = "\"source\": null"
        $texture_key = "\"textures\""
    condition:
        $gltf_header and $texture_key and $null_source
}

Sigma Rule

title: Assimp Null Pointer Dereference Exploit
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects crashes caused by CVE-2026-10197 in applications using Assimp
author: Valters IT
logsource:
    category: application
    product: windows
    service: application
detection:
    selection:
        EventID: 1000
        Provider_Name: 'Application Error'
        Data: '*assimp*'
        Data: '*access violation*'
    condition: selection
falsepositives:
    - Legitimate crashes due to other bugs
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-10197 - Assimp glTF Null Pointer Dereference"; flow:to_server,established; content:"glTF"; nocase; content:"source"; nocase; content:"null"; nocase; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Restrict Local Access: Limit local user access to systems running applications that use Assimp.
2. Monitor for Exploitation: Implement the detection rules above to identify potential exploitation attempts.
3. Apply Workaround: If possible, disable the processing of glTF files or use a different library for parsing them.

Long-Term Fix:

• Apply the official patch once it is accepted and released by the Assimp maintainers.
• Update to a patched version of Assimp (e.g., > 6.0.4) when available.
• Consider using a Web Application Firewall (WAF) or file upload scanner to filter malicious glTF files.

Valters IT Signature

This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.